Crystallization in the Ho 2O 3(Yb 2O 3)GeO 2KFH 2O systems has been investigated under hydrothermal conditions. Crystallization fields of the crystalline phases have been determined. Single crystals of Ho 2Ge 2O 7, Yb 2Ge 2O 7 (two types), K 2HoF 5, K 2YbF 5, K x Yb y Ge p O q ( P-type), Ho(OH) 3, Yb(OH) 3, and K 2Ge 4O 9 have been obtained. The germanates synthesized have been studied by X-ray analysis and infrared-spectroscopy. Diorthogermanate Yb 2Ge 2O 7 has been found to crystallize in two structural types; the first is characterized by the usual structure that is typical for rare-earth germanates, the second is new for germanates of rare-earth elements. High chemical resistance is typical of these crystals. The P-type germanate also has a new type of structure among rare earth germanates. Some suggestions are made as to the structure of these new germanates on the basis of X-ray and ir-spectroscopic data.