Abstract: A gravity gradiometer for measuring off-diagonal components of the gravitational gradient tensor includes a housing comprising a pair of electromagnetic shield enclosures (22, 23) arranged one inside the other, and a body (25) including superconducting material mounted within the inner enclosure (23) for fine pivotal flexure about an axis passing substantially through the center of mass of the aforesaid body. An array of superconducting coils (30) is supported by the outer enclosure (22) and positioned in close proximity to the aforesaid body (25) for diamagnetically applying a rotational force to the body with respect to the axis of flexure and/or for responding by modulation of inductance to pivotal flexure of the body arising from a gravitational gradient across the body. The array is arranged to apply the rotational force in both rotational directions and to respond to flexure in either rotational direction.