The infrared spectrum of the FeH2 radical in the gas phase has been studied in detail between 1605 and 1730 cm(-1), by the technique of carbon monoxide laser magnetic resonance. The molecule is formed in an electric discharge through a mixture of H-2 and Fe(CO)(5) in helium. Many resonances are observed and assigned to transitions in the fundamental band of the antisymmetric stretching vibration 3(0)(1) and in the associated hot band 2(1)(1)3(0)(1). In the latter case, each vibrational level is split into two vibronic components. The measurements are used to determine the parameters of an effective Hamiltonian which is capable of modeling the data to within experimental error. The values determined for the band origin and zero-point vibrational constant are: nu(3) = 1674.7203(3) cm(-1) and B-0 = 3.075 23(5) cm(-1). The data show that the molecule is linear in its ground state and are consistent with an assignment of this state as (5)Delta(g).