Abstract: Mesoporous carbon (MC), prepared by the carbonization of phenol resin using ethylene glycol as a pore forming agent, was used as the catalyst of the counter electrode in dye-sensitized solar cells (DSCs) fabricated by a paste coating method at low temperature, where a non-ionic surfactant, Triton X100, was used as a modifier of the paste. Fractal dimensions (D_F) were used to evaluate the morphological difference of the MC films on the substrate with surfactant content. The efficiency of the DSCs using the MC modified by the surfactant reaches a maximum of 5.65% for 0.6g MC with 0.1 mL surfactant. This is 46.5% higher than that of DSCs using activated carbon as a catalyst in the counter electrode, and 95.4% of the value obtained using DSCs with a Pt counter electrode under the same conditions. The performance improvement of the surfactant-modified MC counter electrode is attributed to a uniform MC film with a low D_F value induced by adding the surfactant, a large average mesopore size of 34.6 nm that is favorable for mass transport, and a high-surface-area glassy carbon structure that has a high content of active sites.