Solar Chimney Power Plant (SCPP) is considered one of the stunts applications for the use of solar energy. The problem lies in this type of power plant in the low rate of power generation on cloudy days and at night. In this study, a mathematical model has been introduced, of a hybrid solar chimney power plant (HSCPP) generating power using solar energy and external heat source. The external heat source is a hot flue gases flows in channels called "Thermal Enhancing Channels (TECh)" located underneath the canopy. Air, as working fluid in t he collector, extracts heat from the channel surface, during the night. This study also proposed a mathematical model to evaluate the performance of HSCPP. The results showed that at solar intensity 1000 W/m2, the temperatures of air inside the collector increased 5.88 after using the external heat source when the wall temperature of the TECh was 100oC. Also the power generation has been enhanced by 23.0. ©2006-2016 Asian Research Publishing Network (ARPN).