A systematic thermophysical characterization of the ionic liquid 1-propylpyridinium tetrafluoroborate has been developed. Thus, the density, speed of sound, refractive index, surface tension, viscosity, ionic conductivity, isobaric heat capacity have been determined over the temperature range (278.15 to 338.15) K. Moreover, thermal events have been investigated over the temperature range (120 to 320) K. A comparison between experimental results for the ionic liquid and 1-butylpyridinium tetrafluoroborate studied has been carried out to analyze carefully how the structural modifications in the cation influence the behavior of these compounds. (C) 2011 Elsevier Ltd. All rights reserved.