The manganese iron cyclotetraphosphate (MnFeP4O12) was synthesized through one-step thermal synthesis at 700 A degrees C using the mixing of manganese and iron metals and phosphoric acid in the presence of water-acetone media. Both FTIR and XRD results indicate the cyclotetraphosphate (P4O12 (4-)) structure and a pure monoclinic phase with space group C2/c (Z = 4). The morphology and crystallite size for the MnFeP4O12 obtained from SEM data and X-ray line broadening show non-uniform particles and 30 +/- A 9 nm, respectively. The magnetic study of the synthesized MnFeP4O12 shows superparamagnetic behavior, which is important for specific application. Some physical properties of the synthesized MnFeP4O12 powder presented for the first time are comparable with those from individual M2P4O12 (M = Mn and Fe) and a binary metal compound as CoFeP4O12.