The performance of three-phase isothermal slurry reactors with continuous gas flow and batch liquid may be affected by gas-bubble-to-liquid and liquid-to-catalyst-particle mass transfer, intraparticle diffusion in the pores of the particles, and adsorption and surface reaction. In dynamic operation, e. g. by introducing a pulse of reactant in the gas feed, the rates of adsorption and surface reaction are not necessarily equal. Equations for a first-order reaction are developed for the zeroth and first moments, in both the effluent gas and the batch liquid, in terms of the separate rate constants for adsorption and surface reaction and the other pertinent rate and equilibrium constants.