A series of Cupper-substituted cobalt nano ferrites (CuxCo1-x Fe2O4 with = 0.00, 0.10, 0.20, 0.30 and 0.4) was synthesized via hydrothermal method. The structural characterizations of all the prepared nanoparticles were performed using powder x-ray diffraction, EDAX and FTIR analyses. These studies confirmed the formation of single-phase spinel structure in at lower compositions. The increase in the value of lattice parameter with increase in Cupper concentration suggests the expansion of unit cell. The surface morphology and particle size of a typical sample were determined using SEM and TEM respectively. The substitution of Cupper strongly influences the magnetic characteristics, and this is confirmed from the magnetization measurements at room temperature.