(P. x) vapor-liquid equilibrium (VLE) data for the (O(2) + C(3)H(8)) binary system were measured using a "static-analytic" method coupled to a gas chromatograph analysis at temperatures of (110.22, 120.13, 130.58. and 139.95) K. Parameters of a proposed thermodynamic profile were adjusted on the basis of experimental VLE data determined in this work, allowing a complete isothermal phase diagram for this hazardous system to be obtained. The vapor-liquid-liquid equilibrium (VLLE) thermodynamic behavior was predicted by modeling and then confirmed by visual observations. On the basis of this work. solubility values of propane in liquid oxygen can be deduced for both the propane-lean and propane-rich liquid phases at temperatures above the melting temperature of pure propane. The device allowing these data to be measured for such a hazardous mixture is also presented, as are the accuracies of the measurements.