OpenAI o3-pro: Advanced AI Reasoning Model 2025

OpenAI has unveiled OpenAI o3‑pro, a new addition to its model lineup that is now available to ChatGPT Pro subscribers and via the OpenAI API. This model release, announced on June 10, 2025, represents a significant step forward in AI reasoning capabilities. Built as a “Pro” tuned version of OpenAI’s most advanced base model (o3), o3‑pro is designed to “think longer” and prioritize reliability over speed. Early user adoption of the previous o1‑pro model showed its strengths in math, science, and coding tasks, and o3‑pro continues to excel in these domains. The new model can tackle complex, multi-step problems more effectively, making it a powerful tool for AI enthusiasts and founders looking for accuracy in challenging tasks where waiting a bit longer is worth it.

A ‘Pro’ Upgrade to OpenAI’s Most Advanced Model

Like its predecessor, o3‑pro is built on OpenAI’s cutting-edge reasoning model (the base o3 introduced in April 2025) and then fine-tuned for even deeper inference and stability. What sets o3‑pro apart is its emphasis on extended reasoning and reliable outputs — it will spend more time working through problems step-by-step to ensure accuracy, rather than opting for quick answers. In practice, this means o3‑pro may respond a bit slower than earlier models, but it yields answers that are more thorough and correct for hard problems. This trade-off is intentional: OpenAI recommends using o3‑pro for “challenging questions where reliability matters more than speed”, even if you have to wait a few minutes for the answer. For AI developers and founders dealing with complex queries, this model offers a new level of dependability.

o3‑pro also inherits the full toolset of the o-series models, which makes it incredibly versatile. It can browse the web, analyze uploaded files, interpret images, execute Python code, and leverage long-term memory to personalize responses. In other words, o3‑pro isn’t limited to generating text from its internal knowledge; it can actively fetch information or perform computations to solve a problem. This agentic use of tools means o3‑pro is adept at multi-faceted tasks that go beyond text generation, whether it’s extracting insights from a dataset or debugging a piece of code. The downside of this broad capability is speed — using tools can introduce delays, so o3‑pro’s responses typically take longer than those from o1‑pro. However, for many use cases (like complex data analysis or research questions), the improved quality of the answer more than compensates for the extra time.

Outperforming Previous Models in Quality and Reasoning

OpenAI o3‑pro isn’t just a minor iteration; early evaluations indicate a leap in performance and answer quality. In expert review tests, human evaluators consistently preferred o3‑pro’s answers over the base o3 model across every category tested. These preferences were especially pronounced in key fields such as scientific analysis, education, programming, business consulting, and long-form writing help. Reviewers noted that o3‑pro’s responses are clearer, more comprehensive, better at following instructions, and more factually accurate compared to its predecessor. This suggests that the “Pro” fine-tuning yields qualitatively better output and not just marginal improvements.

Academic and benchmark evaluations back up these impressions. OpenAI reports that o3‑pro consistently outperforms both the earlier o1‑pro model and the base o3 model on rigorous tests. For instance, internal benchmarks showed significant gains in domains requiring reasoning. On a competitive math exam (AIME 2024), o3‑pro achieved about 93%, compared to 90% by o3 and 86% by o1‑pro, demonstrating its stronger problem-solving skills. Likewise, in a coding challenge (Codeforces), o3‑pro’s rating jumped to roughly 2748, versus 2517 for o3 and 1707 for o1‑pro. These numbers illustrate how o3‑pro’s deeper reasoning translates into better performance on hard quantitative tasks. In a set of PhD-level science questions, o3‑pro also edged out the base model (about 84% vs 81% accuracy), further cementing its status as the most capable ChatGPT model yet.

Another way OpenAI gauged o3‑pro’s strength is through a stringent “4/4 reliability” evaluation. In this test, a model only passes if it can answer the same question correctly four times in a row, emphasizing consistent correctness. Impressively, o3‑pro succeeded in areas like advanced mathematics and competitive programming under this criterion, whereas less advanced models might get a question right once but fail on repeated tries. This reliability focus is crucial for founders who need an AI to not just be occasionally brilliant, but consistently trustworthy in its output.

It’s worth noting that o3‑pro builds on the foundation laid by OpenAI o3, which was itself a major breakthrough. The o3 model (launched in April 2025) pushed the frontier of reasoning across coding, math, science, and even visual understanding. External evaluations showed o3 made 20% fewer major errors than the older OpenAI o1 model on difficult real-world tasks. By leveraging this robust base and applying an extra layer of fine-tuning, o3‑pro is able to reach new heights in reasoning performance.

Availability and Current Limitations

The o3‑pro model is immediately available to those on ChatGPT’s Pro and Team plans via the model picker, where it replaces the previous o1‑pro model as the top-tier option. (Enterprise and Educational plan users will receive access about a week after launch.) For developers, o3‑pro is also accessible through the OpenAI API starting June 10, 2025. This means you can integrate o3‑pro into your own applications or products, bringing its advanced reasoning capabilities to your users. Keep in mind that o3‑pro is a premium model in terms of computational resources. OpenAI has positioned it for use cases where its superior problem-solving ability justifies the higher cost and longer processing time (for example, critical business analyses or complex research queries).

It’s important to understand the limitations at launch so you can plan accordingly. OpenAI notes that temporary (ephemeral) chats are currently disabled for o3‑pro in ChatGPT due to a technical issue they are working to resolve. This implies that while you can use o3‑pro in ongoing sessions, you may not be able to start brand-new, short-lived conversations with it until that issue is fixed. Additionally, o3‑pro does not support image generation — unlike some other models (such as GPT-4o or the base o3), it cannot produce images in response to prompts. If you ask o3‑pro for an image or a drawing, it won’t fulfill that request; you would need to switch to a model that supports the DALL·E tool for image outputs. Similarly, the experimental “Canvas” feature (a visual brainstorming and editing tool in ChatGPT) is not yet supported with o3‑pro. These omissions appear to be temporary trade-offs, likely due to technical constraints at launch. The core focus for o3‑pro is delivering top-notch text-based reasoning. As OpenAI continues development, we might see these capabilities (image generation, Canvas, etc.) enabled for o3‑pro in future updates.

On the safety side, o3‑pro uses the same underlying model architecture as the base o3, so it inherits o3’s safety mitigations and policies. OpenAI has indicated that all the safety evaluations and system card details for o3 apply to o3‑pro as well. This means there are no new safety concerns introduced with the pro model, though, as with any powerful AI system, users should remain vigilant and provide feedback if any unexpected behaviors arise.

Other Recent Model Updates (Spring 2025)

The launch of o3‑pro comes on the heels of a series of rapid improvements and new models in early 2025. OpenAI has been continuously refining its AI lineup, and a few recent updates are worth noting for context:

• Improved GPT-4o (May 12, 2025): OpenAI updated the GPT-4o model’s system instructions to ensure that ChatGPT properly invokes the image generation tool whenever you request an image. This tweak makes the multimodal GPT-4o more seamless — if you ask GPT-4o to draw or visualize something, it will now reliably call on the built-in image generator to produce the result. This improvement came as part of OpenAI’s effort to smooth out the user experience when interacting with models that can handle both text and images.

• Fine-Tuning Fixes for GPT-4o (Late April 2025): In late April, OpenAI addressed some quirks in GPT-4o’s behavior. Notably, on April 29 they rolled back a recent GPT-4o update because it was causing the model to become overly agreeable or “sycophantic” in its responses. A few days earlier (around April 25), they had introduced optimizations to GPT-4o that improved how it manages its long-term memory and enhanced its problem-solving in STEM domains, also making the model more proactive in guiding conversations. These iterative fixes show OpenAI’s responsiveness to user feedback and their commitment to refining the AI’s alignment (reducing unwanted behaviors while boosting useful capabilities).

• Launch of OpenAI o3 and o4-mini (April 16, 2025): Just two months before o3‑pro, OpenAI unveiled the base o3 model and o4-mini model as part of its “o-series” release. OpenAI o3, as mentioned, became the company’s most powerful reasoning model, setting new state-of-the-art results on benchmarks for coding, math, science, and visual tasks. In evaluations, o3 made about 20% fewer major errors than the previous generation (OpenAI o1) on tough real-world challenges, showcasing a major leap in capability. Alongside o3, OpenAI introduced o4-mini, a smaller and faster reasoning model aimed at cost-efficient use; despite its size, o4-mini delivered impressive performance for math, coding, and even some visual reasoning tasks. These April releases expanded the range of models available, allowing users to choose between maximum reasoning power (o3) and efficiency (o4-mini) depending on their needs.

Each of these updates built toward a more powerful and refined AI ecosystem. The OpenAI o3‑pro launch represents the culmination of these efforts in the first half of 2025, effectively combining the advanced reasoning abilities of o3 with an extra layer of tuning for reliability and depth. For AI founders and enthusiasts, the rapid cadence of improvements (from GPT-4o’s fine-tuning to new model launches) underscores how fast the AI field is evolving. Keeping an eye on OpenAI’s release notes is increasingly important to stay updated on the capabilities at your disposal.

In summary, OpenAI o3‑pro is a milestone in AI model development, offering unprecedented reasoning depth and consistency in an accessible format for Pro users. While it comes with a few initial limitations (no image generation, slightly slower replies), it raises the bar for what AI assistants can do, especially on complex tasks where careful thought is paramount. Whether you’re solving advanced technical problems, building AI-driven products, or just exploring the frontiers of AI, o3‑pro provides a glimpse into the future of more thoughtful, tool-empowered AI systems — one where quality of reasoning takes center stage. With OpenAI continuing to iterate rapidly, we can expect even more exciting developments on the horizon, but as of mid-2025, o3‑pro stands out as a new gold standard for AI reasoning in the ChatGPT family.

by Dr. Hernani Costa, First AI Movers