In this work the authors present a structural, morphology and magnetic study of the NiCrxFe2-xO4 spinel nanoparticles (x = 0, 0.3, 0.5, 0.7, 0.9) prepared by a citrate sol-gel method with gel heat-treatment in air at 1100°C in 2 hours. The lattice constant and the size of particle decrease with increasing Cr content. The crystal structure and morphology of the particles was studied by using X-ray diffraction and transmission electron microscopy (TEM). The results showed that the particles form a single phase spinel structure and average particle diameter of about 30 to 40 nm. The effects of Cr substitution on magnetic properties are studied by using vibrating sample magnetometer meter (VSM) in temperature range from 88 K to above Curie temperature in applied fields up to 10 kOe. The spontaneous magnetization Ms, and Curie temperature Tc of the sample decrease with increase in the Cr concentration. The magnetization compensation temperature Tcomp was observed for the samples with x = 0.7 and 0.9.