As the global pursuit of sustainable mobility/transportation intensifies, the need for reducing emissions from conventional vehicles becomes crucial. This thesis addresses this imperative by exploring the integration of advanced energy storage and conversion systems within the framework of Energy Management System (EMS) for electric bus. In recent years, research in Hydrogen Fuel Cell as a source of energy has been growing more and more, especially for heavy transport vehicles such as city buses, and, in particular, coupled with batteries or supercapacitors to eliminate the problem of their slow dynamic response. This thesis is produced to describe, model, and simulate an alternative hybrid powertrain for city bus in order to maximize overall energy efficiency.