In the present chapter, we report physical properties of Co 1-x Ca x Fe 2 O 4 (0.0 ≤ x ≤ 1.0) nano ferrites, prepared by a citrate auto combustion method for technological applications. The evaluation of XRD patterns and HRTEM images indicated fine particle nature. The prepared calcium sample showed orthorhombic phase structure, while the other investigated samples showed cubic spinel structure. The magnetic hysteresis loops at different temperatures (77, 100, and 300 K) were recorded using a vibrating sample magnetometer. The obtained data shows that, the shape of investigated nano ferrite particles can be used as a powerful tool for adapting magnetic properties.