In this communication, an attempt has been made to estimate hourly global solar radiation for the composite climate of New Delhi (latitude: 28.58° N, longitude: 77.20° E, elevation: 216 m above mean sea level) using regression analysis based on the model proposed by Al-Sadah et al. (1990). More than 39000 data of hourly solar radiation on a horizontal surface measured at New Delhi were compared with hourly data calculated by various calculation models. Comparison between estimated and measured values shows that the constants derived for New Delhi provide good estimates of the hourly global radiation except for the morning and evening hours. The present results are comparable with the Liu and Jordan (1960) and Collares-Pereira and Rabl (1979) models which also correlate hourly values and daily totals of the global radiation.