The objective of this study is to present test results and to obtain a dimensionless correlation on the basis of experimental data of an electronic expansion valve (EEV) for R407C (R32/125/134a, 23/25/52 wt.%) and R410A (R32/125, 50/50 wt./%). Several EEVs with different valve needle half tapers were selected as test sections. The mass flow rate through the EEVs was measured for different condensing temperatures and degrees of subcooling at the inlet of the EEVs and evaporating temperatures at the outlet of the EEVs. A new correlation by introducing dimensionless parameters based on extensive experimental data of R407C and R410A to predict the mass flow rate passing through the EEV was presented. The dimensionless parameters were chosen by considering the effects of EEV geometry, inlet conditions and refrigerant properties. The relative deviations for the dimensionless correlation were from -9.65% to 8.68% for R407C and from -12.27%, to 11.36% for R410A. (C) 2006 Elsevier Ltd. All rights reserved.