Abstract: Recently, distributed power generation systems especially with renewable sources have shown a promising result all over the world and have been a technical solution to demand growth for electricity. Among these, solar thermal power plants show a trustworthy source for electricity generation especially for rural areas where small scale solar plants are used. Organic Rankine Cycle (ORC) is a suitable means for electricity generation from low grade heat and has shown a good compatibility with parabolic trough solar collectors (PTC). Here, a PTC integrated with an ORC cycle is being investigated for small scale electricity generation near Tehran. The system includes a solar field, a storage tank, and a small scale ORC engine. Performance evaluation has been done by means of commercial software Thermoflex19. Analysis to find the optimal design point turbine pressure and evaporator temperature for obtaining the best performance shows the effect of turbine inlet pressure and evaporator temperature on various cycle characteristics such as net output work, efficiency, solar heat input, oil temperature, collector efficiency and characteristics of heat exchangers such as pinch point and current UA. A comparison of different working fluids is presented. Results show that benzene has the best performance among fluids butane, n-pentane, iso-pentane, R123 and R245fa for the system conditions described.