Two-dimensional intermolecular potential energy surfaces for the CH(A (2)Delta)-Ar complex (CH bond fixed at equilibrium) have been calculated at the multireference singles and doubles configuration interaction/correlation-consistent valence quadruple zeta level of theory. These surfaces are of 2 (2)A' and 2 (2)A' electronic symmetry. Both potentials define a linear CH-Ar equilibrium structure (Ar...H similar to3 Angstrom), with a secondary minimum for the Ar-CH linear geometry (Ar...C similar to4 Angstrom). The global minimum is similar to 117 cm(-1) below dissociation. Side-on approach of the Ar atom breaks the orbital degeneracy of the (2)Delta state, but this splitting is relatively small near the equilibrium separation, only about 10 cm(-1). The potential surfaces have been used in simulations of the A-X bands of CH/D-Ar. The correlation between the simulated and observed spectra was sufficient for assignment of the latter. Systematic adjustment of the A state average potential, defined as V-a=(V-A'+V-A')/2, was made to obtain a surface that reproduces the vibrational energy spacings and rotational constants of CH/D-Ar.