Google Sets Gemini 4 Hydrogen as Default Model in AI Mode Worldwide and for Hard AI Overview Queries
TLDR
Google has made Gemini 4 Hydrogen the default model in AI Mode worldwide and is using it for the hardest AI Overview questions.
What this Google Search launch means for your site
- Status
- Available
- Platform
- Google Search
- Affects
- AI Mode, AI Overviews, default model
- Who
- Search users worldwide
- Effective
- Not specified in the source
- Action needed
- Not specified in the source
Optimixed Overview
Optimixed's original report on this story.
Google has made Gemini 4 Hydrogen the default model in AI Mode worldwide, and it is also being used to answer the most difficult questions that appear in AI Overviews. Search Engine Journal reports the change applies across all regions.
How we got here: earlier Google Search coverage
On August 14, Google began rolling out Gemini 3.7 Flash to paid Pro and Ultra subscribers in Search's AI Mode, and on August 17 it announced that Search was running on that model. Gemini 3.8 Flash followed on September 2, then Gemini 4 Argon reached AI Mode subscribers on October 13 and Gemini 4 Carbon arrived on November 10. On November 12, Google said Search had been upgraded to Gemini 4 Hydrogen and made it available to every Search user. Now, Google has made Gemini 4 Hydrogen the default model in AI Mode worldwide and is using it for the hardest AI Overview questions.
Summary of earlier coverage
- Nov 12Google Says Gemini 4 Hydrogen Is Its Biggest Search Model Upgrade Yet
Google says its Search has received a major upgrade powered by the Gemini 4 Hydrogen model, which it describes as faster with better understanding, query fan-out, linking, and visual responses.
- Nov 10Google Makes Gemini 4 Carbon Available to Subscribers in Search AI Mode
Google released Gemini 4 Carbon, which is now available to subscribers in Google Search through AI Mode.
- Oct 13Google adds Gemini 4 Argon model to AI Mode for Pro and Ultra subscribers
Google made its Gemini 4 Argon model available through AI Mode for paid subscribers and to developers and enterprises.
- Aug 17Google Shifts Search to Gemini 3.7 Flash, Its Latest AI Workhorse
Google announced Friday that Search is now running on Gemini 3.7 Flash, its newest AI model designed for coding and agentic tasks.