An analytical solution is presented to predict the sloshing response of a cylindrical liquid storage tank with a single-deck type floating roof under seismic excitation. The floating roof is considered to be composed of an inner deck which may be idealized as an isotropic elastic plate with uniform stiffness and mass, and an outer pontoon which can be modeled as an elastic curved beam. The contained liquid is assumed to be inviscid, incompressible and irrotational. The dynamic interaction between the floating roof and the liquid is taken into account exactly within the framework of linear potential theory. By expanding the response of the floating roof into free vibration modes in air and employing the Fourier-Bessel expansion technique in cylindrical coordinates, the solution is obtained in an explicit form which will be useful for parametric understanding of the sloshing behavior and preliminary study in the early design stage. Numerical results are also provided to investigate the effect of the type (single-deck or double-deck) and stiffness of the floating roof on the sloshing response.