The mobility of holes in Cu2O was measured and for certain types of samples found to be very much lower than could have been expected from scattering by lattice phonons. It is proposed that large (10−10 cm2 or greater) space charge limited centers are responsible since these will give the right temperature dependence of the mobility and are compatible with barrier layers around the crystalline copper precipitates present in all samples of Cu2O studied under the electron microscope. The decrease in mobility after heat treatment is explained as resulting from an increased thickness of the depletion layer and resultant increase in size of the scattering center.