For the first time, by applying a modified high-order sandwich shells theory, buckling behavior of two types of porous FG conical sandwich shells are investigated. In the first type, the face sheets and in the second one the core are made of FGM modeled by power law rule that is modified by considering two types of porosity distributions. All materials are temperature dependent and uniform; linear and nonlinear temperature distributions are used to model the effect of the temperature changing in the sandwiches. Governing equations are obtained by a variation principle and solved by Galerkin method. To verify the results, they are compared with FEM results obtained by Abaqus software and for special cases with the results in literatures. Keywords Conical sandwich shell Á Porosity Á FGM Á Temperature dependent Á Buckling List of symbols R 1 , R 2 Small and large radius (m) T Temperature (K) T Time (s) u 0j , v 0j , w 0j Displacements of mid-plane of layers m, n Wave numbers Greek symbols q Density (kg m-3) v, w Curve-linear coordination component c Semi-angle vertex of the cone u v , u w Rotation of normal to mid-plane vector t Poisson ratio e v , e w , e z Normal strains in face sheets and core c vw , c wz , c vz Shear strains in face sheets and core f Porosity volume fraction k v , k w , k z Lagrange multipliers Superscripts T Related to thermal resultant Subscripts j = i, o, c Related to inner and outer face sheets and core