ZnO films on glass tubes were prepared by chemical bath deposition method. The glass tubes were surface-activated by KMnO4(aq) and then submerged in an alkaline aqueous solution, containing Zn(CH3COO)2, NH4OH and HO(CH2)2NH2 at 75 °C to undergo film formation. The microstructures of the dried and calcined ZnO films prepared using different conditions were examined. The films formed on KMnO4-activated glass tubes are composed of steeple-typed wurtzite ZnO columns. Photocatalytic activities of the ZnO films were evaluated by photocatalytically degrading the methylene blue (MB) in water under UV-light irradiation. The apparent reaction order for MB photocatalytic degradation by the ZnO films was 1st-order and the reaction rate constants (k), based on the area of substrates coated by the film, were estimated. The ZnO films prepared using a volume ratio of ammonia/ethanolamine = 2/12 and calcined at 500 °C gave a photocatalytic performance with an average k = 0.549 ± 0.021 L/(m2·min).