The present work is devoted to the study of cryogenic nitrogen jets in sub- and supercritical conditions. A general trend to operate under an increasingly higher combustor pressures is observed in rockets, gas turbines, and diesel engines, primarily due to enhanced effects on thrust, power, or efficiency. In this conditions, the injected fluid(s) may experience ambient pressures exceeding the critical pressure(s) of the propellants, and recent experimental work of Chehroudi et al.1 showed a quantitative similarity to gas jet-like behavior This paper reports an investigation aimed to evaluate the capabilities of a computational method developed for incompressible but variable density flows when applied to supercritical conditions. The predicted initial jet growth rate was compared with available experimental data for liquid/gaseous jets and mixing layers, and showed a good agreement for different density ratios. © 2002 by American Institute of Aeronautics and Astronautics, Inc. All rights reserved.