Surface morphology, structural phases, and electron spin resonance (ESR) measurements were performed for Zn1-xCuxO nanoparticles (x = 0.00, 0.01, 0.02, 0.03, 0.04, and 0.05) synthesized by sol-gel method. The optimum annealing temperature (600 degrees C) and weight loss was clarified using differential thermal analysis (DTA), and thermo gravimetric analysis (TG). By means of X-ray diffraction (XRD) technique, the phase of the samples was defined as single with ZnO wurtzite hexagonal structure and proofed by Rietveld analysis for Zn0.98Cu0.02O sample with calculating c/a rate. Spherical shape random particle distributions were observed in all scanning electron microscope (SEM) measurements. ESR measurements were conducted for all samples and g-value and Delta H (G) values were calculated and correlated from ESR measurements.