The magnetic properties of Mn0.1Sr0.2Co0.7Fe2O4 nanoferrite with particle size of about 8 nm were investigated using magnetization and Mossbauer spectroscopy measurements. The sample shows a large increase in coercive field from 0.045 kOe at room temperature to about 3.00 kOe at 4 K. Room temperature coercive fields increased with increase in the annealing temperature between 300°C and 800°C. Our results show evidence of transformation from single domain to multi-domain structure with thermal annealing.