Shear viscosities of hydrogen (H-2) and helium (He) fluids are investigated at extended regions of temperature and pressure using an improved equation of state, in which the the long-range attractive forces are incorporated into the formalism via the double Yukawa (DY) potential fitted to the empirical H-2 and He potentials. Quantum effects, which become paramount at low temperatures, are taken into account through a first-order quantum correction based on the Wigner-kirkwood expansion. The dirnerization of H-2 is treated as a hard convex body for which an equation of state can be derived based on the scaled particle theory. (C) 2004 Elsevier B.V. All rights reserved.