Most photocatalytic reactions are conducted near room temperature. In this work, we explored photothermal hydrogen production in a carefully designed photo reactor with external heating. Light sources of different wavelength bands were investigated. Formic acid was used as sacrificial regent to study the photothermal hydrogen production activity. Interestingly, the photothermal reaction is not the simple sum of the photo and thermal effects but their synergetic coupling and at 90 degrees C it is 8.1 and 4.2 times of that under photo or thermal conditions alone. With thermal excitation, the bound electrons in Pt can be excited which can easily overcome the energy barrier between Pt and lowest unoccupied molecular orbital of the adsorbed reactants. Activation of the substrate itself by light is also found to be crucial to trigger such photothermal reaction. It is therefore different from traditional plasma resonance induced photothermal reaction where long wavelength IR light is more preferred. (c) 2017 American Institute of Chemical Engineers AIChE J, 63: 2916-2925, 2017