<div class="section abstract"><div class="htmlview paragraph">The present study is performed to examine experimentally the turbulent burning velocity characteristics of lean hydrogen mixtures with attention to the local burning velocity. The special mixtures, having nearly the same laminar burning velocity with different equivalence ratios Ф=0.3~0.9, are prepared. The measured turbulent burning velocities at the same turbulence intensity show to large increase as Ф decreases until about 0.5. Those, however, do not show such large increase when Ф becomes lower than about 0.5. This phenomenon is discussed by the estimated mean local burning velocity taking account of preferential diffusion, tomograms of turbulent flames and estimated Markstein number.</div></div>