The purpose of this study is to define the preparation of CoAl2O4 as a nano-ceramic blue pigment via the polyacrylamide gel method. The powders were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), thermo-gravimetric (TG) and differential thermal analysis (DTA), Fourier transform infrared spectroscopy (FTIR) and UV-visible techniques (UV-vis). Crystallized CoAl2O4 was obtained after calcination at 600 degrees C. The obtained powders in low temperature had a platy structure. By increasing the temperature, the layered structure was crushed into smaller pieces. The average particle size was approximately 18 nm. The UV-vis spectra presented three bands at 551,590 and 628 nm attributed to the Co2+ spin transitions in tetrahedral sites. The results showed that a different calcination temperature causes a variation in the color and size of the particles. The temperature for obtaining blue CoAl2O4 was about 1000 degrees C. (C) 2014 Elsevier B.V. All rights reserved.