In this paper, the comparison study of photocatalytic oxidation properties of TiO2 and ZnO-quantum dots (QDs) in gaseous phase was designed and performed to degrade acetaldehyde (CH3CHO) first time. The obtained results showed that the 1st order rate constant for the prepared QDs of ZnO (1.9 x 10(-2)/min) is one magnitude higher than that of Degussa P-25 (83 x 10(-3)/min). The efficiencies were found to be 70% and 92% for Degussa P-25 and ZnO-QDs respectively in 120 min of reaction time. The QDs were prepared from zinc nitrate hexahydrate (Zn(NO3)center dot 6H(2)O), n-propylamine and SDS surfactant in 6 h refluxing. The crystallinity of the product was analyzed with X-ray diffraction (XRD) and it reveals that prepared QDs size is very small and it exhibit wurzite phase. The general morphology of prepared QDs were observed with using FESEM and TEM, which showed that the average size are in the range of similar to 6-7 nm. The elemental and compositional analysis was also carried out with FTIR spectroscopy. (C) 2013 Elsevier B.V. All rights reserved.