The increasing sophistication of heat transfer calculations and evaluations have shown the need for accurate and consistent transport property data on halogenated hydrocarbons. The previous data on liquid viscosity of halogenated refrigerants covers over three decades in time. The various sets of data are not only often in poor agreement but in terms of modern needs the omissions are serious.This study was undertaken to provide the refrigeration industry with a complete and reliable set of liquid viscosity data covering the commonly used refrigerants as well as the newer azeotropes for which no previous data existed.