A simple photoelectrochemical method was proposed to quantitatively evaluate the electron transport process of photoelectrocatalytic oxidation of water at vertically aligned nanotubular TiO₂ photoanodes. The photoelectrocatalysis reaction resistance (R = k/Jsph+R0 = RI+R0) was measured and used to express the electron transport characteristics of the nanotubular TiO₂ electrode. The overall resistance was found to consist of a variant (RI) and an invariant component (R0). The RI was found to be inversely proportional to the saturation photocurrent and depends on the experimental conditions. The proportional constant, k, represents the minimum applied potential bias required to remove 100% of the photogenerated electrons from the photocatalyst layer and was found to be independent of the anodization time. The invariant component of the resistance (R0) is an inherent property of the semiconductor photocatalyst that represents the sum of ohmic contact impedance at the conducting substrate/TiO₂ interface and crystalline boundaries impedance. The magnitude of R0 linearly increased with anodization time. The real saturated photocurrent density (Jreal-sphd) was found to be independent of R0 indicating the electron collection efficiency is independent of nanotube length.