Metal-oxide-semiconductor capacitors with sputtered 100 nm thick copper gates, operated at 180 degreesC, are sensitive to NO2, with no cross sensitivity either to H-2 or CO, in inert atmospheres and air. Sensitivity to NO is present in air only. Flatband voltages shift positive with NO2 stimulus, similarly to gold gates of comparable morphology, but responses are an order of magnitude smaller. Unlike Au, response and relaxation times are independent of NO2 concentration and the signal is affected by negative drift, due to gate oxidation. Ultraviolet photoelectron spectroscopy measured changes of the work function upon NO2 adsorption, which are larger for copper than gold, are not representative of the corresponding gate-dielectric change.