The use of immobilized enzyme reactors in biotechnology and biomedicine is rapidly expanding. This study concentrates on hollow-fiber (HF) enzymic reactors for continuous, single-pass operation. The enzyme, in a soluble form, is physically confined within the shell section of the reactor and the substrate solution flows through the lumen section of it. We consider here a two-substrate reaction proceeding via the Ping-Pong mechanism, with substrates and reaction products diffusing through the fiber wall. The developed analytical model enables to calculate the expected conversion as a function of the volumetric flow rate, kinetic constants, diffusion coefficients, geometric dimensions of the reactor, the flow regimen in the apparatus and substrates concentrations. The model equations are solved by a numerical procedure and the system performance is simulated. Depending on the operation conditions employed, the reactor is controlled by kinetic processes, diffusion processes, or both.