The mobility of C(+) in He gas has been measured using a very low temperature drift tube mass spectrometer at 77 and 4.3 K. Ion mobility separation between the ground-state C(+) ((2)P(degrees)) and the metastable C(+) ((4)P) ions has been observed at the effective temperature T(eff) from 550 to 1500 K. The calculation of the mobility based on the classical momentum transfer theory has been carried out using the interaction potential provided by the multi-reference electron correlation method. The calculated mobility of C(+) qualitatively agrees with the measurement, confirming the accuracy of the interaction potential between the metastable ion and He.