In this paper the test results of a performance evaluation of new alternatives; R-407B, R-507, R-408A and R-404A as substitutes to CFC-502 are presented. The test results were obtained using an air-source heat pump with enhanced surface tubing under standard ARI conditions. The data demonstrated that, as an interim replacement, R-408A blend has a superior performance among the proposed blends including R-502, in the range investigated. Furthermore, the alternatives to R-502 are characterised by high discharge pressure compared to R-502. In particular, R-407B and R-408A have higher discharge temperatures compared to R-502.