Absorption data for COS and N2O in aqueous solutions of N-methyldiethanolamine (MDEA), ethylene glycol, and sulfolane (tetrahydrothiophene 1,1-dioxide) at 298 K and solubility data for COS in water at temperatures ranging from 298 to 338 K are presented. Also density, viscosity, N2O solubility, and N2O diffusivity data are reported for a wide range of aqueous alkanolamine solutions, aqueous mixtures of alkanolamines, and solutions of MDEA in water/ethanol. It is shown that an analogy between COS and N2O with respect to gas solubility in aqueous solutions of ethylene glycol and sulfolane holds up to about 25 mass %. This seems to justify, for engineering purposes, the application of this analogy for the estimation of COS solubilities in diluted aqueous amine solutions. Direct verification of a COS-N2O analogy was provided by absorption of N2O and COS into aqueous MDEA solutions in a laminar film reactor.