In this work, sol-gel auto-combustion technology is used to synthesize nanocrystalline Ni0.2Cu0.2Co0.6Fe2O4 with high purity metal nitrate and citric acid as precursor solution. The prepared samples are sintered at different temperatures (400 degrees C, 500 degrees C, 600 degrees C, 700 degrees C, 800 degrees C, 900 degrees C, 1000 degrees C and 1100 degrees C) for 3.5 h. The structure and magnetic properties of the samples are characterized using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and vibrating sample magnetometer (VSM). The analysis of the XRD patterns confirms that all the samples have a single-phase cubic spinel structure. The particle size of the prepared samples (between 23 nm and 36 nm) is determined by the Scherrer equation. The effect of particle size is through observation of samples sintered at different temperatures. FT-IR spectroscopy shows the characteristic peak is near 588 cm(-1). And the measurement also confirms the formation of spinel structure. The magnetic parameters of the samples are measured by VSM at room temperature with a maximum magnetic field of 1 T. Coercivity, remanent magnetization and saturation magnetization change with the changing sintering temperature. It can be clearly observed that the magnetic properties increase significantly with the temperature increasing from 600 degrees C to 700 degrees C. The dM/dH versus m curves are obtained by differentiating the hysteresis loop. The increasing peak height of dM/dH at H-m, indicates a magnetically stable state for the samples with good crystalline cubic spinel structure.