Performance and flow characteristics of a conical microthruster operated in cold thruster mode are presented. Nitrogen, Argon and Carbon dioxide were used as the medium. The performance parameters (specific impulse, impulse efficiency, thrust coefficient and characteristic velocity) are measured. The chamber pressure was varied from 2.8 bar to 12 bar. It is found that the high viscous loss severely degrades the performance of the thruster at a pressure below 5 bar. However, the mass flow remains unaffected even at a low pressure. The computed Mach number shows that at low pressures flow separates earlier. The schlieren photographs show the flow development inside the thruster at different pressures. Interestingly, a highly asymmetric flow field exists in the nozzle expansion section. Row perturbation effects cause the flow to separate from the upper wall and to remain attached with lower wall.