In this study, the buckling of thin truncated conical shells made of functionally graded materials (FGMs) subjected to hydrostatic pressure is investigated. The material properties of functionally graded truncated conical shell are assumed to vary continuously through the thickness. The variation of properties followed an arbitrary distribution in terms of the volume fractions of the constituents. The fundamental relations, the stability and compatibility equations of FGM hybrid truncated conical shells are obtained. Using Galerkin's method, these equations were transformed to pairs of time-dependent differential equations and then hydrostatic buckling pressure expression was obtained. Numerical calculations have been made for fully metal, fully ceramic, Si(3)N(4)/Ni and ZrO(2)/Ti-6Al-4V truncated conical shells. The results reveal that the volume fraction distributions have a significant effect on the buckling pressure of FGM hybrid truncated conical shells. Finally, results are validated through comparison of obtained values with those in the literature. (C) 2008 Elsevier Ltd. All rights reserved.