Thermal conductivity kappa of a single crystal triclinic 4-bromobenzophenone polymorph was measured along axis b from 4.5 to 303 K. The kappa values versus temperature were represented as a sum of kappa(1), which generally describes the thermal conductivity of ordered crystals, and kappa(TA) responsible for activation processes, which fits nicely experimental data from 120 up. DFT analysis led to the conclusion that the activation agent responsible for the high-temperature behavior is the molecular mode that involves C-Br oscillations. It is for the first time that the exponential thermal conduction was ascribed to a specific intramolecular excitation. (C) 2016 Elsevier B.V. All rights reserved.