We aimed to investigate the stability and particle properties of antibody by means of spray drying process. A Plackett-Burman factorial design was applied to identify the main factors of formulation and process which significantly influenced the responses. The formulations were consisting of the antibody as well as different ratios of either mannitol or trehalose as stabilizer. The spray drying parameters were inlet temperature, air flow rate, solution concentration, liquid feed rate and aspiration percent. Spray drying yield, particle size, size distribution, moisture content and protein stability were evaluated as the responses. Size exclusion chromatography as well as Fourier transform infrared (FTIR) spectroscopy was used to investigate remained antibody monomer and secondary structure, respectively. Particle size distribution was between 2.48 and 10.2 mu m by narrow distribution of 0.71 to 1.96. The results of this study indicate that atomization flow rate and type of sugar with various ratios could efficiently enhance particle properties. (C) 2012 Published by Elsevier B.V.