This work presents the saturated second Virial coefficient of new environmentally friendly refrigerants 1,1- difluoroethane (R152a) , 1,1,1,3,3-Pentafluorbutane (R365mfc) and their mixture. The vapor phase behavior of the mixture was investigated using the Virial equation of state combined with group contribution method of modified UNIFAC. https://www.theijire.com/archives/paper-details?paperid=46&papertitle=drenched-virial-quantity-of-the-environmentally-friendly-refrigerant-fluids-r365mfc