The pure rotational spectrum of calcium isocyanide, CaNC, in its (0,0,0) X(2) Sigma(+) vibronic state was measured using a combination of Fourier transform microwave (FTMW) and pump/probe microwave-optical double resonance (PPMODR) spectroscopy. Gaseous CaNC was generated using a laser ablation/supersonic expansion source : The determined spectroscopic parameters are (in MHz), B=4048.754 332 (29); gamma=18.055 06 (23); b(F)=12.481 49 (93); c=2.0735 (14); and eQq(0)=-2.6974 (11). The hyperfine parameters are qualitatively interpreted in terms of a plausible molecular orbital descriptions and a comparison with the alkaline earth monohalides and the alkali monocyanides is given.