Carbon dioxide (CO2) emission and fresh water scarcity have become two huge global issues over the last decades, and CO2 hydrate-based technology was promoted and developed to address them. This study investigated the effects of methylcyclopentane (MCP) on the hydrate formation condition and CO2 capture efficiency. Five cases and 31 cycles experiments of different MCP/water molar ratios (ranging from 0 to 0.03) in salt solution and porous media were conducted using the isochoric method. The hydrate phase equilibrium data of CO2–MCP hydrates were measured, and meanwhile the CO2 capture efficiencies were calculated. The results indicated that the rising MCP concentrations increase both the hydrate equilibrium temperature and the gas uptake. After the comparisons of the interpolated hydrate gas uptakes at uniform hydrate phase equilibrium pressure of 3 MPa among CO2–MCP, CO2–CP (cyclopentane), and CO2–C3H8 (propane) hydrates, CO2-MCP hydrates are especially suitable for CO2 capture. It should be noted that M...