Hall effect measurements in CH3NH3PbBr3 single crystals reveal that the charge-carrier mobility follows an inverse-temperature power-law dependence, mu proportional to T-gamma, with the power exponent gamma = 1.4 +/- 0.1 in the cubic phase, indicating an acoustic-phonon-dominated carrier scattering, and gamma = 0.5 +/- 0.1 in the tetragonal phase, suggesting another dominant mechanism, such as a piezoelectric or space-charge scattering.