Progress in the understanding of polymer synthesis, including the crucial step of initiation and undesired side reactions, and in characterization of polymers, especially their thermal behaviour, are directly related to advances in calorimetric technologies. In polymer synthesis, since polymerization reactions are highly exothermic, reaction calorimetry (RC) is an appropriate technique for on-line process monitoring. Measurements are non-invasive, rapid, and straightforward. Viscosity increase and fouling at the reactor wall are typical features of many polymerizations. The global heat transfer coefficient, UA, also changes drastically when viscosity increases and affects the accuracy of calorimetric measurements. Our approach was focused on oscillating temperature calorimetry (TOC). Reactions were performed with two different reaction calorimeters, i.e. an isoperibolic calorimeter and a Calvet-type high sensitivity differential calorimeter, respectively. Special attention was paid to the interpretation of the measured signals to obtain reliable calorimetric data. The evolution of heat transfer coefficient was followed by performing two Joule effect calibration experiments, before and after the reaction, and the two values interpolated to obtain the desired profile of UA. A differentiation method based on the convolution of the measured heat flow by the generated one was used for determining the time constants and deconvoluting the measured heat flow. With respect to polymer characterization, pressure-controlled scanning calorimetry, also called scanning transitiometry, is now a well established technique. The transitiometer was coupled to an ultracryostat to work at low temperature. The assembly was used to follow the pressure effect on phase change phenomena such as fusion/crystallization and glass transition temperature T-g of low molecular weight substances or high molecular weight polymers. (c) 2006 Elsevier B.V. All rights reserved.