Nano-sized single-phase Mn3O4@ZnO core-shell nanocomposite was prepared via a simple one-pot sequential polyol using triethylene glycol as a high boiling point solvent as well as a reducing agent. The presence of both Mn3O4 and ZnO was confirmed with X-ray diffractometry. Infrared measurements proved the presence of triethylene glycol on the surface of Mn3O4@ZnO core-shell. The average particle size is between 8 and 13 nm. Reference intensity ratios method calculations showed that the weight percentage of phases were found as 54.7 % ZnO and 45.3 % Mn3O4. The lower Tc maybe explained by interface effects and dominant ZnO shell in magnetic properties of core-shell nanocomposite.