Nanocrystalline ZnO films were deposited onto glass substrates in the temperature range of 473-673 K using pulsed spray pyrolysis. The structural, substructural, and optical properties of the films were investigated by means of X-ray diffraction analysis, Raman scattering, and Fourier transform infrared (FTIR) spectroscopy. The effect of the substrate temperature (T s ) on the coherent scattering domain (CSD) sizes L, microstrains e, and microstress s grades, and the average density of dislocations r in the films were estimated through the broadening of X-ray lines using the Cauchy and Gauss approximations and the threefold function convolution method. The ZnO films grown at T s ¼ 623-673 K possessed the highest values of L, and the lowest of e, s, and r, indicating high-crystalline quality. The Raman spectra showed peaks located at 95-98, 333-336, 415, 439-442, 572, and 578-584 cm À1 , which were interpreted as E 2 low (Zn), (E 2 high ÀE 2 low ), E 1 (TO), E 2 high (O), A 1 (LO) and E 1 (LO) phonon modes of the ZnO wurtzite phase. The FTIR spectra showed relatively weak signals at 856, 1405, and 1560 cm À1 , corresponding to the C-H and C-O stretching modes, in addition to the main Zn-O mode at 475 cm À1 , indicating a low content of precursor residues.