The FeH2 radical has been detected in the gas phase through the observation of transitions in the fundamental band of the antisymmetric stretching vibration nu(3). The molecule was generated in an electrical discharge through a mixture of hydrogen and iron pentacarbonyl in helium and the signals were recorded by the technique of laser magnetic resonance. It is established that the molecule is linear in its ground state and that this state is (5) Delta in character; theoretical calculations suggest that it has gerade symmetry. The vibrational band origin is determined to be 1674.7195(4) cm(-1) and the rotational constant for the (0,0,0) level is 3.01328(3) cm(-1). This latter value corresponds to an r(0) Fe-H bond length of 0.1665 nm.