Experimental measurements of burning rates rates and modeling comparisons were performed for lean H2/ O2/diluent flames spanning a wide range of conditions: equivalence ratios from 0.30 to 1.0, flame temperatures from 1400 to 1800K, pressures from 1 to 25 atm. The experimental data show negative pressure dependence of burning rate at high pressure, low flame temperature conditions for all equivalence ratios. The models of Davis et al. and O'Connaire et al. predict the experimental data within ∼30% for the conditions studied. In general, substantial differences are observed between literature model predictions and the experimental data as well as among model predictions themselves - up to a factor of four at high pressures.