Thermal radiation impact on magnetic nanofluid heat transfer in a curved cavity is studied. Impact of external magnetic source is taken into account. Innovative numerical method is chosen namely CVFEM. Impacts of radiation parameter (Rd), Rayleigh (Ra), Hartmann (Ha) numbers and volume fraction of Fe3O4 (phi) on hydrothermal treatment are examined. Results indicate that temperature gradient enhances with augment of Ra; phi, but it reduces with rise of Rd; Ha. Lorentz forces cause the nanofluid velocity to reduce and augment the thermal boundary layer thickness. Impact of radiation becomes stronger for higher buoyancy forces. (C) 2016 Elsevier B.V. All rights reserved.