This paper proposes an acceleration mechanism to explain the observations of energetic particles in the inner magnetosphere of Jupiter. In the inner magnetosphere particles are convected towards and away from the Io plasma torus by the centrifugally driven interchange mode or by the longitudinal asymmetry of the magnetosphere and the Io plasma torus. They experience a varying (space-dependent in Jupiter's frame of reference) magnetic field and are subject to pitch-angle scattering by wave-particle interactions. Thus, an e-fold magnetic pumping acceleration is expected in the system. The calculations show that the accelerator can generate up to one MeV energy particles in about 10--15 times the characteristic convection time. ¿ American Geophysical Union 1993