An experimental investigation has been carried out for small liquid bi-propellant thrusters of 490 & 1500 N levels. These thrusters have to operate for more than 100 sec in continuous and pulse mode. In this case, film cooling is the primary mode of thruster cooling. The thruster uses hydrazine based propellant as fuel and N2O4 as oxidiser. Film cooling is carried out by injecting a fraction of fuel from an injector periphery. Unlike impinging type injection elements are used for core flow. The thruster’s shell used for testing was made of stainless steel and di-silicide coated C103 material. A 1D heat transfer model was developed for predicting the thruster outer wall temperature. The experimental investigation was carried for different film cooling percentage and injector configuration was modified for each case. Thermocouples were mounted on top & bottom side of shell for temperature measurement. Infrared camera also used for recording temperature in the test. Based on experimental investigation, effective film cooling percentage for optimum thruster performance has been estimated for two thrust levels and these studies also helped in validating the heat transfer model.