The invention relates to the field of magnetohydrodynamic generators, and more precisely to such a generator (10) comprising a working fluid flow passage (11) that is defined by a first wall (12) and a second wall (13), an ionizing device (14) for ionizing the working fluid, a pair of arms (15), each connecting together the first and second walls (12, 13) downstream from said ionizing device (14) so as to define, within the flow passage (11), a channel (16) between said arms (15) and said walls (12, 13), said channel (16) being arranged to be traversed by a portion of the working fluid after it has been ionized, a magnet for generating a magnetic field (B) oriented in a direction that is perpendicular to the flow of the working fluid through the channel (16) defined by the pair of arms (15) and said walls (12, 13), and at least one pair of electrodes (17), each of the electrodes (17) in each pair being arranged on a respective side of the channel (16) defined by the pair of arms (15) and said walls (12, 13), said electrodes (17) in each pair being spaced apart from each in a direction that is perpendicular to said magnetic field (B) and to the flow direction of the working fluid through the channel (16) defined by the pair of arms (15) and by said walls (12, 13).