Rates of effusion of zirconium tetrabromide, between 400 and 500 K, depend on the orifice size. Using Motzfeldt's method, an equilibrium vapour pressure equation was obtained as log(p/bar)=–5569/T+ 8.937, giving ΔH= 106.62 ± 3.55 kJ mol^–1 and ΔS= 171.12 ± 1.51 J deg.^–1 mol^–1 for the sublimation process.