A new binary Co 1/2 Fe 1/2 (H 2 PO 4 ) 2 ·2H 2 O was synthesized by a simple, rapid and cost-effective method using CoCO 3 –Fe(c)–H 3 PO 4 system at ambient temperature. Thermal treatment of the obtained Co 1/2 Fe 1/2 (H 2 PO 4 ) 2 ·2H 2 O at 600°C yielded as a binary cobalt iron cyclotetraphosphate CoFeP 4 O 12 . The FTIR and XRD results of the synthesized Co 1/2 Fe 1/2 (H 2 PO 4 ) 2 ·2H 2 O and its final decomposed product CoFeP 4 O 12 indicate the monoclinic phases with space group P2 1 /n and C2/c, respectively. The particle morphologies of both binary metal compounds appear the flower-like microparticle shapes. Room temperature magnetization results show novel superparamagnetic behaviors of the Co 1/2 Fe 1/2 (H 2 PO 4 ) 2 ·2H 2 O and its final decomposed product CoFeP 4 O 12 , having no hysteresis loops in the range of ±10,000Oe with the specific magnetization values of 0.045 and 12.502emu/g at 10kOe, respectively. The dominant physical properties of the obtained binary metal compounds (Co 1/2 Fe 1/2 (H 2 PO 4 ) 2 ·2H 2 O and CoFeP 4 O 12 ) are compared with the single compounds (M(H 2 PO 4 ) 2 ·2H 2 O and M 2 P 4 O 12 ; where M=Co, Fe), indicating the presence of Co ions in substitution position of Fe ions.