Google's Gemini 4 Hydrogen replaces 3.8 Flash, 2.5x faster

Google's elemental naming scheme has moved away from the descriptive Pro/Flash labels, but Hydrogen's role is unchanged: it is the faster, more economical model that most people in Google's ecosystem actually use. What is different this time is the release process. The recent Argon and Carbon models were staged, starting with cybersecurity researchers and, even at general availability, limited to users paying for Google's most expensive AI subscription.

Hydrogen skips those gates. Access began immediately, and the model has already replaced Gemini 3.8 Flash across the company's products. Google's stated gains are speed and reliability: it runs in one of four thinking levels (low, medium, high, and the new xhigh), and even in high mode it is 2.5 times faster than Flash 3.8. Google's analysis also puts the reduction in fabricated claims at more than 5x.

On code generation, Google says Hydrogen more than triples 3.8 Flash's score on Terminal-Bench, and in some cases it trades blows with the higher-tier Argon — scoring 54 on the Artificial Analysis Intelligence Index in xhigh mode versus 50 for Argon. That positioning suggests the cheaper tier is narrowing the gap with Google's premium model, though the comparison rests on Google's own analysis and on benchmark scores rather than independent testing.