This paper presents a comparison between experimental and numerical results regarding the operation of a capillary pump loop evaporator. Two cylindrical evaporators were tested, with different heated porous lengths, one with 20 mm and another with 40 mm. Both have 22 mm external diameter, a 9 mm porous thickness and 80 mm porous length. Water was used as working liquid. The loop was made from copper tubes and the evaporator from copper porous wick covered with aluminum with grooves formed in the inner surface. All tests took place in horizontal level using heat load applied to the evaporator surface from an 85 W electric resistance. The experimental measurements were compared with the predictions of a 3-dimensional CFD model of the evaporator and were found to be in satisfactory agreement.