Nanomagnets with controlled size distribution are produced by continuous hydrogen reduction technique and coated in situ by carbon or copper. The copper layer can be oxidised ex situ. The coated nanomagnets are well-protected against oxidation occurring over time or in elevated temperatures. The optical and electrical properties of the magnets are controlled by coating. The coating can also be functionalised. The saturation magnetization of all nanomagnets is close to that of bulk, Co, indicating a highly crystallised structure and the avoidance of oxidation. Copper coating increased the measured magnetic hysteresis. (c) 2012 Elsevier B.V. All rights reserved.