Natural gas is considered as excellent alternate fuel due to its clean-burning characteristics and extensive availability. Its higher-octane rating enables use of higher compression ratio, hence higher thermal efficiency of the engine. However, main drawback remains is the power loss due to lower volumetric efficiency and lower flame speed compared to gasoline. In this project CNG is used in a dual-fuel mode in direct injection spark ignition (DISI) engine, where a large fraction of energy is supplied by port-injection of CNG and remaining by direct-injection of gasoline. It helps in reducing in particulate emissions from DISI engines as well. The objective of this project is to assess feasibility of CNG-gasoline in dual-fuel mode in Direct Injection Spark Ignition (DISI) engine.