The metal-rich portion of the Co-Ni-P system was studied experimentally at 800 °C by means of evacuated silica glass tube technique. Five binary phases: Co2P Ni2P, Ni12P5, Ni5P2, Ni3P and five ternary phosphides solid solutions: (Co1−x,Nix)3P, λ1−(Ni1−xCox)2P (hexagonal), λ2−(Co1−xNix)2P (orthorhombic), (Co1−x,Nix)12P5 and (Co1−x,Nix)5P2 were found to be stable in the system. Cobalt has a significant influence on the structure of (Ni,Co)2P solid solutions and, therefore, cobalt contents might change the crystal structure of naturally occurring phosphides with the Ni/P = 2:1 ratio. Ni-rich, cobalt-containing phosphides with the Ni/P ratio = 3:1 and 2:1, isotypic with minerals schreibersite and barringerite, could possibly be found in meteorites. Likewise, phosphides with Ni/P ratio = 12:5 and 5:2 may possibly be found, but in close association with natural Ni-rich phosphides.