A fast, yet accurate algorithm for calculating CO2 15-μm band cooling rates by Curtis matrix interpolation is presented based on a computationally efficient method to compute correlated-k coefficients in an inhomogeneous atmosphere for any spacing in pressure levels and variation of CO2 mixing ratio. The algorithm produces an error in cooling rate of less than 4% in the region where the radiative processes play a major role. This algorithm is easy to use and can be readily adopted for use in general circulation models of the Earth's atmosphere. ¿ American Geophysical Union 1992