Gold nanorods (Au NRs) have been widely exploited for various biomedical applications due to their strong two-photon photoluminescence (2PPL). 2PPL of Au NRs were found significantly quenched in organic solvents, which was originally ascribed to reduced luminescence yields caused by electron transfer quenching. It was recently found that excitation of 2PPL of Au NRs involved two sequential one-photon absorption steps. Here various ultrafast spectroscopic techniques have been employed to demonstrate two different solvent-to-metal electron transfer pathways: electron transfer from organic solvents to sp and d band holes of excited Au NRs, which have different influences on 2PPL of Au NRs. Electron transfer to sp band holes occurs extremely fast (∼25 fs), which blocks absorption of the second photon and reduces overall two-photon excitation efficiency, which is the dominant mechanism for the observed 2PPL quenching. In contrast, electron transfer to d band holes hinders the radiative recombination process an...