七氧化四铽化学式为Tb₄O₇。

棕褐色无定形粉末，不溶于水，溶于热浓酸中生成铽(Ⅲ)盐类。七氧化四铽与1:1浓乙酸和盐酸混酸中回流反应半小时，发生歧化生成二氧化铽和三氯化铽。

Terbium(III,IV) oxide, occasionally called tetraterbium heptaoxide, has the formula Tb₄O₇, though some texts refer to it as TbO_1.75. There is some debate as to whether it is a discrete compound, or simply one phase in an interstitial oxide system. Tb₄O₇ is one of the main commercial terbium compounds, and the only such product containing at least some Tb(IV) (terbium in the +4 oxidation state), along with the more stable Tb(III). It is produced by heating the metal oxalate, and it is used in the preparation of other terbium compounds. Terbium forms three other major oxides: Tb₂O₃, TbO₂, and Tb₆O₁₁.