In this study, methane (purified biogas having 100% methane fraction) is used as primary fuel in dual fuel and HCCI modes. Diesel and DEE are used as secondary fuels in dual fuel and HCCI mode respectively. Applied load is varied from 10% to 90% of rated load. In dual fuel mode, diesel is injected in conventional way (in-cylinder injection). In HCCI mode, DEE is injected at the intake port or in the intake manifold. Performance, emission and combustion characteristics are compared for all three modes viz. Diesel mode, Dual fuel mode and HCCI mode. Dual fuel mode exhibits high efficiency at high load. HCCI mode produces ultra-low NOx and smoke emissions. © Asia-Pacific Conference on Combustion, ASPACC 2019.All right reserved.