A multigeneration energy system produces several useful outputs form one or more kinds of energy inputs. The main purposes of using multigeneration are to increase efficiency and sustainability, and to reduce environmental impact and cost. Such systems often provide significant potential for global warming mitigation. Possible products of a multigeneration system include electricity, heating, cooling, hot water, fresh water and hydrogen. In this paper, a comprehensive thermodynamic modeling is performed of a multigeneration system based on a heat recovery unit, an organic Rankine cycle (ORC), an ejector refrigeration cycle, a domestic water heater and a proton exchange membrane (PEM) electrolyzer that produces hydrogen.To assess the irreversibility in each component and system performance, exergy analysis is utilized, which is a useful analysis and design tool. To understand system performance more comprehensively, a parametric study is performed of the effects of several important design parameters on energy and exergy efficiencies of the system.