The interaction between plasmonic metal catalysts and visible light can be exploited to increase their catalytic activity. This activity increase results from the generation of hot charge carriers or hot surfaces, or a combination of both. We have studied the light-induced Suzuki-Miyaura cross-coupling reaction of bromobenzene and m-tolylboronic acid using Pddecorated Au nanorods as plasmonic catalyst in order to assess which physical effect dominates. Comparative experiments under laser illumination and in dark were performed, demonstrating that under the experimental conditions applied in our study the catalytic activity achieved upon illumination is dominantly based on the conversion of light to heat by the plasmonic catalyst. Pd leached from the catalyst also plays a significant role in the reaction mechanism.[a] M.