The effect of composition on the Curie temperature of kappa-phase (Fe, Mn)(3)AlCx was investigated by thermomagnetometry analysis (TMA). Results reveal that increasing carbon content decreases the Curie temperature, while manganese has little effect. Serrations in the magnetization versus temperature curve of Fe3AlCx found at about 100 degrees C, may arise from the fluctuation of carbon atoms between Site I and 11 Of K-phase unit cell. (c) 2005 Elsevier B.V. All rights reserved.