An empirical model for determining the monthly average daily global solar radiation on a horizontal surface for Makurdi, Nigeria (Latitude 7 degrees 7'N and Longitude 8 degrees 6'E) was developed using the Angstrom Page equation. The solar radiation (W/m(2)), hours of bright sunshine and cloudiness were measured hourly from 0600 H to 1800 H daily for 18 months. The constants 'a' and 'b' of the Angstrom linear type equation were determined by plotting the clearness index (H/H(o)) against the possible sunshine hours (n(s)/N) to obtain the line of best fit. The constant 'a' was obtained from the intercept of the line on the y-axis while the constant 'b' was obtained from the slope of the line. The developed model for determining the global horizontal solar radiation at the location was H = H(o) [0.17 + 0.68(n/N)] with a coefficient of correlation of 0.78. The mean bias error and root mean square error that were used to test the performance of the constants were 0.17% and 1.22% respectively. The measured solar radiation was compared with the solar radiation predicted by the model and no significant difference was found between them using F-LSD at P <= 0.05. (C) 2011 Elsevier Ltd. All rights reserved.