The work presented in this paper is an attempt to evaluate the performance and combustion characteristics of a hydrogen-ethanol dual-fuel combination with different percentage substitutions of hydrogen (i.e., 0-80% with an increment of 20% by volume) and at three different compression ratios of 7:1, 9:1, and 11:1. Experimental investigations have been carried out on a computer-interfaced, four-stroke cycle single-cylinder compression ignition (CI) engine, which was converted for spark ignition (SI) and carburetion. The effect of the compression ratio and increase in percentage of hydrogen substitution on the performance parameters, rate of heat release, and pressure were determined, and the results obtained are reported in this paper.