Coupling the corresponding states theory with the dimensional analysis method, the viscosity correlations for calculating gas-phase viscosity at normal pressures were proposed by correlating the non-dimensional viscosity eta* with the reduced temperature T-r and the critical compressibility factor Z(C). The correlations would apply to monatomic gases, diatomic gases, hydrocarbons and halogenated hydrocarbons. Compared the calculated results with literature data, the absolute average of relative deviations (AADs) of the correlations are 0.47% for monatomic gases, 0.57% for diatomic gases, 0.37% for hydrocarbons and 0.43% for halogenated hydrocarbons, respectively. Meanwhile, the viscosity correlations of five halogenated hydrocarbons R32. R125, R134a, R143a and R152a were presented. The correlations were established by correlating the reduced residual viscosity Delta eta(r) and the reduced density rho(r) on the base of the corresponding states theory. Compared the calculated results with literature data, the AADs of the correlations are 2.16%, 2.39%, 1.10%, 1.41% and 1.38%, respectively. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.