The standard (p degrees = 0.1 MPa) molar enthalpies of formation, at T = 298.15 K, in the condensed phases of two alkylpyrazoles, viz. 3-methylpyrazole and 1,3,5-trimethylpyrazole, were determined by static bomb calorimetry. Calvet microcalorimetry was used to measure the standard molar enthalpy of vaporisation of 1-methylpyrazole and the standard molar enthalpy of sublimation of 1,3, 5-trimethylpyrazole. From these two sets of results, the standard molar enthalpies of formation of both alkylpyrazoles in gaseous phase, at T = 298.15 K, were derived. [GRAPHICS] The final results were analysed and discussed in terms of molecular structure. (c) 2007 Elsevier Ltd. All rights reserved.