The nanoparticles of chromium substituted nickel ferrite with the general formula NiCrxFe2-xO4 (x = 0.0, 0.2 and 0.4) were prepared by sol-gel auto combustion method using ascorbic acid as a fuel. The single phase cubic spinel structures of all the samples were confirmed through X-ray diffraction (XRD) analysis. The lattice constant, X-ray density and bulk density was obtained and their variations with Cr substitution were studied. The lattice constant decreases with Cr substitution. The crystallite size of all the samples was determined using Debye-Scherrer’s formula and found to be 28-36 nm which confirms the nanocrystalline nature of the samples. The DC electrical resistivity was studied using two probe technique to understand role of chromium on electrical behaviour. The variation of DC resistivity with temperature exhibits semiconductor behaviour. The resistivity decreases with increase in temperature.