A simple compact retarding-potential Mott polarimeter is described that operates at an electron accelerating voltage of 25 kV. With a thorium target the instrument provides efficiencies eta [=S2eff(I/I0), where Seff is the effective asymmetry (Sherman) function and I/I0 is the scattering efficiency] of approximately 1.3 x 10(-4) which are similar to the best values obtained using earlier Mott polarimeters. The present instrument, however, occupies a much smaller volume and is suitable for a wide range of applications involving angle- and/or energy-resolved polarization measurements.