This paper addresses the problem of reflection and transmission of compression waves at the phase transition layer between the vapour and liquid phases of the same fluid. Within the framework of second gradient fluid modeling, we use a non-convex free energy in order to describe the phase transition phenomenon. A stationary solution for the fluid density is found for an infinite domain, and an analytical expression for the phase transition is presented. Then the propagation of linear waves superposed to this stationary solution is discussed, with particular attention to the behaviour in correspondence of the interfacial layer. The reflection and transmission of waves is studied and analized with the aid of numerical simulations, and an interesting phenomenon of mass adsorption at the interface is observed and discussed.