The phase transitions of n-C22H46 have been measured by using a high resolution and super-sensitive DSC. The crystal-rotator transition and the rotator-melt transition were observed both in the heating and in the cooling run, although a rotator-rotator transition was observed only in the cooling run. A new peak was found at about 3 K above the 'bulk' melting temperature. It is considered to be due to the order-disorder transition of a monolayer on the surface of the liquid alkane. When the cooling rate was below 0.1 mK s(-1), the peak due to solidification was separated to give another phase transition. (C) 2003 Elsevier B.V. All rights reserved.