The dynamic behavior of a horizontal boiling channel with a surge tank is investigated through a nonlinear analysis. The surge tank is subject to a constant inlet flow rate and the outlet pressure-flow rate relation of the downstream boiling regime is described by a constitutive model containing a cubic nonlinearity. Within certain operating regimes, the model exhibits self-excited periodic oscillations which can be identified with pressure-drop oscillations. In this study. these oscillations are described as relaxation oscillation and the qualitative features of the response can be understood in terms of the underlying model. Finally, the present model is compared with the experimental data available in literature.