Transitions in the fundamental and first hot bands of the GeH radical have been detected previously by CO laser magnetic resonance. The transitions occur within both2Π3/2and2Π1/2manifolds. Additional resonances associated with the R(1/2) transition in the2Π1/2component are reported in this paper. These data have been fitted with previously published data for GeH and GeD to determine the parameters of a single model effective Hamiltonian which describes all naturally occurring isotopomers.