This work reports results obtained from heat flux measurements performed during the deposition of metallic thin films by low-pressure plasma sputtering. It introduces a sensitive diagnostic, which allows to perform such measurements directly during the process and to follow in real-time mechanisms involved in plasma/surface interaction. Although quantitative results are provided and discussed, the main scope of this article is a qualitative study of the sputter-deposition process via the energy flux transfers. The diagnostic developed for energy flux measurements is presented and the versatility of the experimental apparatus is described. Results on the study of the deposition of Pt (and Fe) thin films demonstrate a good reproducibility of the measurements and the ability to separate the energetic contributions of the main plasma (∼ 300 mW/cm 2) from the deposition process ones (2 to 23 mW/cm 2). The influence of gas pressure, plasma power and target bias voltage, on the energy transferred to the silicon substrate is also studied.