The results presented in this paper were focused on the synthesis of monophasic spinel cadmium ferrite (CdFe2O4) by sol-gel combustion. The effect of various reducing agents such as citric acid, glycine and urea on the phase purity of the CdFe2O4 was studied. The phase composition was determined by X-ray diffraction and the particle size measured by scanning electron microscopy (SEM). Analysis confirmed the formation of monophasic CdFe2O4 powder with an average particle size of 0.3 μm after synthesis at 900°C with urea, as a reducing agent. Practical use of synthesized CdFe2O4 powders as gas sensors was demonstrated.