In this study, we formed an algorithm to find refrigerant mixtures of equal volumetric cooling capacity (VCC) when compared to CFC based refrigerants in vapor compression refrigeration systems. To achieve this aim the point properties of the refrigerants are obtained from REFPROP where appropriate. We used replacement mixture ratios-of varying mass percentages-suggested by various authors along with our newly formed mixture ratios. In other words, we tried to see the effect of changing mass percentages of the suggested (i.e. in the literature) replacement refrigerants on the VCC of the cooling system. Secondly, we used this algorithm to calculate the coefficient of performance (COP) of the same refrigeration system. This mechanism has provided us the ability to compare the COP of the suggested refrigerant mixtures and our newly formed mixture ratios with the conventional CFC based ones. According to our results, for R12 R290/R600a (56/44) mixture, for R22 R32/R125/R134a (32.5/5/62.5) mixture, and for R502 R32/R125/R134a (43/5/52) mixture are appropriate and can be used as replacements. (c) 2005 Elsevier Ltd. All rights reserved.