The characteristics of solids particles in pulsating flows are investigated. A model based on the momentum equation is developed and applied to solid inert particles in the gas flow of the Rijke-type pulsating combustor, by using a computational scheme based on a fourth order Runge-Kutta method. For application of the model, two types of particles are considered: coal ash and elutriated material from coal combustion. The velocities and trajectories of the particles are obtained, showing that pulsations decrease the particle residence time and increase the rate of particulate emission. The decrease in residence time becomes more significant when the particle diameter is close to the cut diameter, i.e., the diameter for which the particle starts to rise in the ascending gas flow of the combustor. The cut diameter is found to be independent of the type of regime, pulsating or non-pulsating. The phase between particle and flow velocities is found to depend on particle size and density. For coal-ash-type particles, for example, those with diameters lower than 5 mm follow the pulsating flow at zero phase and those with diameter higher than 120 mm possess a velocity 1 2 p out of phase with the flow velocity. The phase for particles between 5 and 120 mm will be between 0 and 1 2 p.