This paper experimentally investigates the effect of hydrogen addition on the lean burn capability of an ethanol-fuelled Wankel rotary engine at Wide Open Throttle (WOT) operating conditions in order to observe the resultant engine economy and the hydrocarbon emissions. During the tests, a monorotor Wankel engine operating at 3000 rpm was modified to run on an ethanol-hydrogen blend with 0% and 5% hydrogen energy fractions in the intake. The excess air ratio was varied from 1.7 to the Ultra-Lean Operating Limit (ULOL) of a specified hydrogen-ethanol mixture. With hydrogen addition, the test results show that the ultra-lean operation limit of pure ethanol fuelled Wankel engine was extended and the engine stability was enhanced. Moreover, the engine fuel economy was increased and Hydrocarbons (HC), Carbon Monoxide (CO) and Carbon Dioxide (CO2) emissions were reduced after hydrogen addition. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.