The phase transitions of even n-alkanes, n-C34H70, n-C36H74, n-C40H82 and n-C42H86 with high purity have been measured using a high resolution and super-sensitive DSC. A new transition in the low temperature phase was observed in all the samples in the heating run. The surface freezing phenomenon was observed by thermal measurement for the first time in all the samples both in the heating and in the cooling run. The difference of the thermal behaviors between the heating and cooling run was also observed in all the samples. (c) 2006 Elsevier B.V. All rights reserved.