A combination of in situ annealing and electron backscattered diffraction in the SEM has been used to determine the mobility of high angle grain boundaries in a deformed single-phase Al–Si alloy. It is found that the boundary velocity is directly proportional to the driving pressure and that the activation energy for boundary migration over all the conditions investigated is consistent with control by lattice diffusion of the solute. It is confirmed that tilt boundaries of recrystallized grains misoriented by 40±10° about axes within ±10° of 〈111〉 have an increased mobility compared to other high angle boundaries, whereas the mobilities of 40°〈111〉 twist boundaries are similar to those of general high angle boundaries. The mobility maximum for the 40°〈111〉 tilt boundaries is very broad, which is in contrast to the sharp mobility peaks reported for curvature-driven grain growth, and possible reasons for these differences are discussed.