Nanoparticles of Co 0.1 Zn 0.9 O were successfully synthesized by a simple polyethylene-glycol (PEG)-assisted hydrothermal method. A systematic investigation was done to determine the structural, morphological and magnetic properties of the as synthesized sample and XRD, FE-SEM and EDX measurements were conducted respectively for the structural, morphological and compositional investigation of the product. For the magnetic property investigations VSM was used. Additionally FMR was further used to confirm the room temperature ferromagnetism of the sample. Average particle size of the nanoparticles was estimated using Debye-Scherer׳s equation and found as 23.5nm. SEM image of the nanoparticles confirms that the size of the nanoparticles vary between 20nm and 100nm with small aggregation. Magnetization measurements have shown that the particles have room temperature ferromagnetic behavior with relatively high coercive fields which are decreasing with the temperature as expected. FMR spectrum also confirms the room temperature ferromagnetism of the product without any metallic precipitates.