The AlCH₃ molecule has been observed by both neutralization-reionization mass spectrometry (NRMS) and resonance-enhanced multiphoton spectroscopy (REMPI), and GaCH₃ is a target molecule for both experimental techniques. Ab initio quantum mechanical methods have accordingly been applied to GaCH₃. GaCH₃ is predicted to have a C_3v equilibrium geometry, and theoretical values of its rotational constants, vibrational frequencies and infrared intensities are presented.