An accelerometer comprises a substrate (10) mode of silicon and a torsion beam (R4) spanning a V-shaped recess (11) formed in a major surface of the substrate. In one embodiment the centre of mass C of the torsion member is offset from the pivot axis XX, the accelerometer being responsive to a lateral acceleration acting transversely of the torsion beam. In another embodiment the centre of mass C lies on the pivot axis XX, the accelerometer being responsive to a rotational acceleration acting about the pivot axis. A multi-axis accelerometer includes one or more of the lateral and rotational accelerometer in combination.