The invention relates to a hydrogen sensor (8) and a method for its production, a measuring device (2), and a method for measuring a hydrogen concentration. The hydrogen sensor (8) for measuring a hydrogen concentration in an environment (4) includes a substrate (10) on which a hydrogen-absorbing sensor medium (14) is applied as a thin film in a sensor region (12) communicating with the environment. The sensor medium (14) changes its volume depending on a hydrogen concentration in the sensor medium (14), and said change of the volume causes a variation of a mechanical strain introduced by the sensor medium (14) in the substrate (10). In a preferred embodiment, the substrate (10) of the hydrogen sensor (8) is a piezoresistive semiconductor, at least within the sensor region (12).