A numerical investigation is conducted to study an H-2 - O-2 rocket nozzle flow in chemical and vibrational nonequilibrium. Therefore, a 9 reactions kinetic model was implemented in our two-temperature house code. The vibrational relaxation times taken from Skrebkov's theoretical model and utilized in our simulations are found to be better suited for the H-2 - O-2 mixture than those evaluated using Millikan & White semi-empiric formula. The utilized 9 reactions kinetic model demonstrates a good modeling of the chemical nonequilibrium. The results show the presence of three regions in propulsive nozzles: an equilibrium region, a nonequilibrium region followed by a return to equilibrium region. Vibrational nonequilibrium effects on flowfield parameters and nozzle performances in fuel-rich flows of H-2 - O-2 rocket are investigated, by comparing this baseline simulation to vibrational equilibrium simulation. Vibrational nonequilibrium effects on flowfield parameters and on nozzle performances are computed and shown to be minor. A reduction of 90% of computation time is observed when using the vibrational equilibrium configuration instead of the vibrational nonequilibrium configuration. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.