Lien et al. (Adv. Mater. 2006, vol. 18, p. 98) reported on photocurrent generation in SWNT thin films suspended across metal electrodes at zero bias and the effect was attributed to the Schottky contacts formed at the nanotube-metal interfaces. By performing a set of independent experiments and tests on similarly engineered two-terminal devices and analyzing the results reported in said paper we show that the response is not associated with the contacts or temperature-induced conductance change (bolometric effect), but is instead caused by an optically induced thermovoltaic effect.