Google Sets Gemini 4 Hydrogen as Default Model in AI Mode Worldwide

2026-11-15 · Digital Living

Google has made Gemini 4 Hydrogen the default model behind AI Mode in every market. It is also being used to answer the hardest questions in AI Overviews.

Google has changed the model that powers AI Mode. Gemini 4 Hydrogen is now the default, and the change applies worldwide rather than in a limited set of regions.

The model is also being used in AI Overviews, but only for the hardest questions. That suggests Google is sending its most complex queries to this model, while simpler ones may be handled differently.

The report, published by Search Engine Journal, gives few further details. It does not say how the change affects which sites are cited, how traffic is distributed, or how ads appear in these results.

For businesses in Thailand and elsewhere, the main point is that Google's AI-driven search experiences are now running on a newer default model everywhere. Complex, multi-part questions are the kind of query most likely to be affected.

Takeaway for businesses: Test your most important and complex customer questions in AI Mode and AI Overviews, and note how your brand and content show up so you can adjust your content strategy.

Sources: https://www.searchenginejournal.com/google-gemini-4-hydrogen-default-ai-mode/597096/