The invention mainly relates to a method for assisting the starting of a hybrid pneumatic engine comprising a thermal engine (10) and a pneumatic reservoir (11) communicating with cylinders (12) of said thermal engine (10) by means of pneumatic valves (13), said method comprising the step of injecting pressurized air into said cylinders (12) from the pneumatic reservoir (11) by opening the pneumatic valves (13) of said thermal engine (10) so as to increase a mass of air enclosed in said cylinders (12) in the intake phase, characterized in that said method comprises the prior step of pressurizing said pneumatic reservoir (11) by activation of a starter (25) of said thermal engine (10), and opening of said pneumatic valves (13) in the compression phase when the pressure in said cylinders (12) becomes greater than the pressure in said pneumatic reservoir (11).
