GPT-5.4 Pro is OpenAI's most powerful reasoning model, built on the GPT-5.4 architecture with extended compute for tackling the most complex tasks. It features a 1M+ token context window with support for text and image inputs, and uses additional thinking time to deliver consistently higher-quality answers on difficult problems in coding, mathematics, research, and multi-step planning. The model supports configurable reasoning effort (medium/high/xhigh) along with web search, file search, computer use, and image generation, making it the premium choice for professional workflows where accuracy and depth justify longer response times.