Solar radiation data are required by solar engineers, architects, agriculturists and hydrologists for many applications such as solar heating, cooking, drying and interior illumination of buildings. In order to achieve this, several empirical models have been developed to predicted the solar radiation all over the world. The main objective of this study is to review the global solar radiation models available in the literature. In order to evaluate the applicability of 50 models for computing the monthly average daily global radiation on a horizontal surface, the geographical and meteorological data of Konya, Turkey (37 degrees 52'N latitude, 32 degrees 29'E longitude) was used. The models were compared on the basis of statistical error tests such as the percentage error (e), mean percentage error (MPE), root mean square error (RMSE), mean bias error (MBE), regression coefficient (R) and Nash-Sutcliffe equation (NSE). According to the results, the Ertekin and Yaldiz model showed the best estimation of the global solar radiation on a horizontal surface for Konya, Turkey, by means of the MPE (0.004266%), RMSE (0.022576 MJ/m(2)), MBE (0.000000 MJ/m(2)), R (0.999993) and NSE (0.999985) statistical tests: H = 20.296019 - 0.096134H(0) + 0.3175936 - 0.146422RH + 10.705159 (S/S-0) -0.288332T + 0.021331TS + 0.359791C + 0.207588P - 0.076444E (c) 2006 Elsevier Ltd. All rights reserved.