In this paper, we study the longtime asymptotic behavior of a phase separation process occurring in a three-dimensional domain containing a fluid flow of given velocity. This process is modeled by a viscous convective Cahn-Hilliard system, which consists of two nonlinearly coupled second-order partial differential equations for the unknown quantities, the chemical potential and an order parameter representing the scaled density of one of the phases. In contrast to other contributions, in which zero Neumann boundary conditions were are assumed for both the chemical potential and the order parameter, we consider the case of dynamic boundary conditions, which model the situation when another phase transition takes place on the boundary. The phase transition processes in the bulk and on the boundary are in the unknowns ρ, the order parameter, and µ, the chemical potential. In the above equations, τ Ω is a nonnegative constant, f ′ is the derivative of a double-well potential f , and u is a given velocity field.Typical and significant examples of f are the so-called classical regular potential, the logarithmic double-well potential , and the double obstacle potential , which are given bywhere the constants in (1.3) and (1.4) satisfy c 1 > 1 and c 2 > 0, so that that f log and f 2obs are nonconvex. In cases like (1.4), one has to split f into a nondifferentiable convex part (the indicator function of [−1, 1] in the present example) and a smooth perturbation. Accordingly, one has to replace the derivative of the convex part by the subdifferential and interpret the second identity in (1.1) as a differential inclusion.As far as the conditions on the boundary Γ := ∂Ω are concerned, instead of the classical homogeneous Neumann boundary conditions, the dynamic boundary condition for both µ and ρ are considered, namely,