In this work, generalized correlations for the estimation of Henry’s constants of nonpolar solutes in molten polypropylene (PP) and poly(dimethylsiloxane) (PDMS) were proposed based on the available relationships for molten polyethylene (PE) and polyisobutylene (PIE). Furthermore, the available relationships for nonpolar solutes were modified and extended to estimate Henry’s constants of polar solutes in molten polymers, and generalized correlations for PDMS and low-density PE(LDPE) were developed. The proposed correlations enable one to estimate Henry’s constants of nonpolar solutes in molten PP and PDMS and those of polar solutes in molten PDMS and LDPE from the critical temperature, critical compressibility factor, and acentric factor of the solute for a wide temperature range with good accuracy, which are convenient and useful for engineering purposes.