Thioglycolic acid (TGA) capped hydrophilic fcc-FePt magnetic nanoparticles (MNPs) were directly synthesized by a facile one pot polyol method. Thioglycolic acid (TGA) was used to functionalize the nanoparticles by incorporating thiol group onto the surface. It helped in the preparation of highly stable dispersions of nanoparticles with spherical morphology. A possible formation mechanism for these FePt MNPs, depending on the role of TGA, was proposed. The as-prepared FePt MNPs possessed a face centered cubic structure with an average size of 6 +/- 1 nm and superparamagnetic property at room temperature. MM study showed that these MNPs exhibited a transverse relaxivity of similar to 600 mg(-1) ml s(-1), superior to that of reported iron oxide nanoparticles. (C) 2015 Elsevier B.V. All rights reserved.