Plasmon catalysis is an interesting technology concept for powering chemical processes with light. Here, we report the use of various Al2O3-supported Ru spheroidal nanoparticles as catalyst for the low-temperature conversion of CO(2)and H(2)to CH4(Sabatier reaction), using sunlight as energy source. At high loadings of Ru spheroidal nanoparticles (5.9 % w/w), we observe a sharp increase in the rate of the sunlight powered reaction when compared to the reaction in dark at the same catalyst bed temperature. Based on our results we exclude plasmon coupling as cause, and attribute the rate enhancement to collective photothermal heating of the Al2O3-supported Ru nanoparticles. ; R.H., J.R., F.S., N.M., M.X., P.B. (all TNO), K.E. (IMEC), A.H., M.K.V.B. (both Hasselt University) and T.d.H. (Zuyd University of Applied Sciences) acknowledge financial support from the European Fund for Regional Development through the cross-border collaborative Interreg V program Flanders-The Netherlands (project LUMEN), co-financed by the Belgian province of Limburg and the Dutch provinces of Limburg and Noord-Brabant. M.A.V. acknowledges Solliance and the Dutch province of Noord-Brabant for funding the TEM facility. ; den Hartog, T; Buskens, P (corresponding author), Netherlands Org Appl Sci Res TNO, High Tech Campus 25, NL-5656 AE Eindhoven, Netherlands ; Zuyd Univ Appl Sci, Appl Sci Acad, Nieuw Eyckholt 300, NL-6400 AN Heerlen, Netherlands ; Hasselt Univ, Inst Mat Res Design & Synth Inorgan Mat DESINe, Agoralaan Bldg D, B-3590 Diepenbeek, Belgium. tim.denhartog@tno.nl; pascal.buskens@tno.nl