Three different fuels, methane, methanol, and hydrogen, were tested to investigate their effects on the operation of a rotary engine by measuring the output power, torque, and exhaust air temperature. The results showed that the output power with methanol was lower than those with methane and hydrogen at the same engine speed. Methanol enabled the engine to have the widest operation range from 5000 to 18000 revolutions per minute (RPM). The engine using hydrogen and methane operated stably in the ranges of 6000 to 10000 RPM and 7000 to 14000 RPM, respectively. Methanol had greater efficiency than hydrogen and methane, and hydrogen had higher output power and torque than methane and methanol. To use methanol for a rotary engine, a higher-pressure pump is required, and a mixture of liquid and gas fuels enables better operation than the use of methane or hydrogen.