The preparation and characterization of a series of high symmetric tysonite type compounds in SrF2-MF3 (M = Yb3+, Er3+) system are reported. A complete solid solution formation between the two end-members, namely SrYb3F11 (Sr0.25Yb0.75F2.75) and SrEr3F11 (Sr0.25Er0.75F2.75) was observed in the series SrYb3-XErXF11 (0.0 less than or equal to X less than or equal to 1.0). The magnetic measurements of the end members show the presence of Er3+ and Yb3+ as free ions with a magnetic moment of 4.6 mu (B) for the former and 9.7 mu (B) for the latter. Even in the solid solution, the M3+ ions exist without any mutual interaction and showed an average magnetic moment, viz. 10.5 mu (B) for SrYb1.5Er1.5F11.