We investigate reactive and non-reactive strained flows associated with high pressure cryogenic rocket engines. A detailed high pressure fluid model based on thermodynamics of irreversible processes, statistical mechanics as well as kinetic theory of dense gases is used. This model insures the positivity of chemical entropy production and of molecular transport related entropy production. We first investigate a mixing layer between cold hydrogen and oxygen and the dramatic influence of nonideal transport near thermodynamic instabilities. Diffusion and partially premixed H-2-O-2 transcritical flame structures are then studied as well as strain extinction limits and dilution extinction limits. (c) 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved.