Diffuse solar radiation has been correlated with relative sunshine duration and extraterrestrial solar radiation as well as with global solar radiation at Ibadan, Nigeria. On the basis of these correlations, empirical equations have been proposed with their associated coefficients calculated by fitting the available experimental data to obtain a linear Angstrom type equation and to a quadratic form. When both global solar irradiation and relative sunshine duration data are available, the recommended equation for Ibadan is: