From an experimental point of view, full-field measurement techniques have increasingly been used since the 1980s to study the deformation processes of materials. These techniques provide surface measurements without any contact with the specimen under study. In particular, infrared (IR) cameras are used to capture temperature fields. This technique has been widely applied to metals, polymers and composite materials (see for instance Refs. [22], [23] and [24]), but rarely to elastomeric materials [25], [26] and [27]. The present paper aims at analysing the temperature variations obtained by IR thermography during the deformation of natural rubber in order to characterize the thermal response of such crystallizable rubber under mechanical loadings. One of the main issues is to link the changes in the microstructure, which occur at the microscopic scale, to the corresponding temperature variation measured at the macroscopic scale.