High-yield ZnO spheroidal nanoparticles with an average diameter around 23 nm (≈ 25% frequency) and 30 nm (≈ 28% frequency) were obtained by controlled semicontinuous precipitation at low temperatures. This synthesis was obtained from hydrozincite (Zn5(CO3)2(OH)6) as primary nanoparticles. The Zn5(CO3)2(OH)6 nanoparticles were synthesized by hydrolysis of Zn(NO3)2 in aqueous solution of (NH4)2CO3 and later, the precipitation becomes. Two temperatures of 60 and 70 °C in combination with three times of reaction were tested; followed by calcination of the precipitate at 400 °C. This range of sizes of nanoparticles is comparable with those obtained by other methods reported in the literature, such as microemulsions, however, here the advantage was not using solvents or surfactants. The ZnO nanoparticles were characterized by energy dispersive X-ray spectroscopy coupled to a scanning electron microscopy (SEM-EDS), transmission electronic microscopy (TEM), and X-ray diffraction. The antibacterial activity of the films against Gram-positive (S. aureus) and Gram-negative (E. coli.) bacteria was investigated using the disc diffusion method. The best results were found in the inhibition zone for Gram-positive bacteria, when the concentration of ZnO NPs incorporated was 3 mg disc-1.