Diesel engine emissions are highly complex mixtures. They consist of a wide range of organic and inorganic compounds distributed among the gaseous and particulate phases. Particulates and NOx emissions are the important components of the Diesel exhaust. The composition of Diesel exhaust varies considerably, depending on engine type, operating conditions, fuel, and lubricating oil. In this research, the effects of supercharging, which is one of the engine operational parameters, on Diesel emissions have been investigated. For this purpose, a comprex, CX (pressure wave supercharger) was designed and manufactured and then matched to an indirect injection Diesel engine. During the engine tests, the emission parameters (CO, SOx, NOx and smoke density) have been observed and measured for different pulley ratios at full load conditions. The results showed that CX supercharging may be an alternative way of NOx reduction with some modifications.