Recent research on high and medium entropy alloys revealed that the CoNiCr-system provides interesting properties, however, the high temperature strength of such single-phase alloys is not sufficient. Therefore, new high temperature superalloys based on the CoNiCr-system and strengthened by γ'-(Ni,Co)₃(Cr,Al,Ti) precipitates have been developed, and the effect of different refractory element additions was investigated in the present work. Energy Dispersive X-ray measurements in an Scanning Transmission Electron Microcope and High Energy X-ray Diffraction were employed to determine the elemental partitioning behavior and the lattice misfit between the γ and γ' phases. Ta and Nb strongly concentrate within the γ' phase, whereas Mo weakly partitions to the γ phase. W distributes equally between the γ and γ' phases. These new superalloys have an unexpectedly high positive misfit compared with some conventional Ni-based superalloys and Co-based superalloys. Nb and Ta additions increase the lattice misfit further, while Mo and W decrease the lattice misfit. Alloying with Mo and W can suppress the formation of discontinuous precipitate colonies at grain boundaries. The effect of refractory elements alloying on the yield stress at room temperature was evaluated by analyzing the contributions of different strengthening mechanisms. Based on theoretical considerations alloying with Nb or Ta will significantly improve precipitation strengthening by increasing the antiphase boundary energy. Mo has the highest solid solution strengthening effect in the γ phase, followed by W. Compared with some conventional Ni-based superalloys, the investigated new CoNiCr-based superalloys exhibited better mechanical properties at high temperature, which indicates that these alloys are possible candidates for high temperature applications.