The performance of a new hollow-fibers-in-tube type pertractor has been studied. This pertractor consists of a hydrophilic tube in which a bundle of hydrophobic hollow fibers is inserted. An n-alkane fraction was used as the membrane phase. Pulsation of this phase increases the mass flux by more than 40% at a relatively low pulse velocity and reaches a maximum value at about 10 mm.s-1. Wettability of the microporous walls plays an important role. A substantially higher mass flux, by about 60%, can be reached when the stripping solution is in contact with the hydrophilic wall. Analysis of the mass-transfer resistances has revealed that the main resistance is found in the liquid membrane phase, especially in the phase soaked into the hydrophobic pores. The values of the mass flux per unit volume of the pertractor ranged from 9 to 20 mol-m-3.h-1.These values are much higher than those obtained with other bulk and supported liquid membranes and are comparable with emulsion-type liquid membranes.