For the first time in HfO 2 -Yb 2 O 3 and ZrO 2 -Yb 2 O 3 solid solutions fast luminescence with a characteristic time of ~20ns was observed, it was attributed to the charge transfer process involving the states of Yb 3 + ion and adjacent oxygen in as-grown crystals. The maxima of the luminescence bands were at 280 and 430nm. Luminescence excitation spectra and decay kinetics are presented. Annealing of the samples for 12h at 1000 o C in air resulted in a considerable change in the luminescence properties of HfO 2 -Yb 2 O 3 crystals: a new band with enhanced yield peaking at 360nm at room temperature and 400nm at 6K appeared with a characteristic decay time of ~25ns, which was attributed to Yb 2 + .