Homogeneous Charge Compression Ignition (HCCI) combustion has attracted widespread interest as a combustion system that offers the advantages of high efficiency and low exhaust emissions. However, it is difficult to control the ignition timing in an HCCI combustion system owing to the lack of a physical means of initiating ignition like the spark plug in a gasoline engine or fuel injection in a diesel engine. Moreover, because the mixture ignites simultaneously at multiple locations in the cylinder, it produces an enormous amount of heat in a short period of time, which causes greater engine noise, abnormal combustion and other problems in the high load region. The purpose of this study was to expand the region of stable HCCI engine operation by finding a solution to these issues of HCCI combustion. The results of previous studies have shown that the application of supercharging when using a fuel blend of dimethyl ether and methane moderates the rapid rate of combustion, resulting in two-stage heat release during the main combustion period under certain specific operating conditions. The mechanism producing two-stage heat release has been made clear by spectroscopic measurements and exhaust gas analysis using a Fourier transform infrared spectrometer.In this study, the possibility of expanding the high-load operating region of an HCCI engine was investigated by applying supercharging and exhaust gas recirculation, which are known to be effective for operating an HCCI engine at high loads.