The Curie temperatures and the electrical resistivity at 4.2°, 78°, and 300°K have been measured for nickel‐carbon solid solutions containing up to 1.5 at.% carbon. The resistivity at 4.2°K increases at the rate 3.48±0.06 &mgr;&OHgr; cm/at.% carbon; whereas the Curie temperature decreases by ∼30 C°/at.% carbon. The electrical resistivity shows positive apparent deviations from Matthiessen's rule. The variation of the Curie temperature is consistent with donor theories in which carbon donates both itspelectrons to thedband of the metal. The susceptibility shows an unusually large field dependence near the Curie temperature presumably because of as yet unclassified modifications of the nickel moment due to the presence of carbon.