The CH(A (2)Delta)-Ar van der Waals molecule provides a prototypical example of a (2)Delta state complex. The rovibronic structure of CH/D(A)-Ar has been examined by recording rotationally resolved spectra for the A-X transition. The spectra are dominated by vibrational progressions of the intermolecular stretch in combination with two bending states. Rotational energy level patterns were consistent with a linear equilibrium geometry for CH(A)-Ar. Parity splittings resulting from vibronic interactions were below the resolution of the present measurements. Spectra for the A-X transition of CD, recorded incidentally in this study, reveal an error in the previously accepted assignment of the 0-0 band R-2(1/2) line.