In this work the volumetric behavior in a broad range of temperatures (283.15 K-333.15 K) and pressures (0.1 MPa-65 MPa) of two pyridinium-based ionic liquids, namely: 1-ethyl-2-methylpyridinium bis(trifluoromethylsulfonyl)imide and 1-propyl-2-methylpyridinium bis(trifluoromethylsulfonyl)imide, is presented. The density pressure temperature data have been correlated successfully with two empirical equations: Tait and TRIDEN equations. Using these equations, relevant derived properties such as isobaric expansibility and isothermal compressibility have been obtained. Finally, the Paduszynski-Domanska group contribution method has been used to predict the volumetric behavior of our ionic liquids; a reasonable agreement between experiment and predicted data is found. (C) 2014 Elsevier B.V. All rights reserved.