The formation of oxide phases at 900 °C in the system Fe2O3-“Pr2O3” was investigated. With a decrease in the molar fraction of Fe2O3 a corresponding increase in PrFeO3 was observed. For equal molar fractions of Fe2O3 and “Pr2O3” the formation of PrFeO3 and very small fractions of α-Fe2O3 plus an addi¬tional oxide phase, which could not be identified with certainty, were observed. With further increase in “Pr2O3” fraction the praseodymium oxides Pr6O11 and PrO2 started to become dominant in the phase com¬position. The small fraction (< 0.02) of the same unidentified oxide phase was also obtained when Pr(OH)3 was calcined in air at 900 °C ; this was probably a mixture of other praseodymium oxides with different average oxidation numbers of Pr. The results of XRD, 57Fe Mössbauer and FT-IR spectroscopies are discussed.