This study aims at investigating the emissions of cathode gas-phase polycyclic aromatic hydrocarbons (PAHs) from a single direct methanol fuel cell (DMFC) at different operating parameters (methanol concentration, methanol flowrate, oxygen flowrate, and cell temperature). At the standard test condition (run A1), the concentrations of stage 1 (S1) and S2 PAHs ranged from non-detect (ND) to 10.3 ± 2.54 (Nap) and ND to 0.148 ± 0.047 (IND) µg Nm–3, respectively; furthermore, the Total-PAHs and Total-BaPeq concentrations of S1 + S2 were 21.2 ± 4.48 µg Nm–3 and 409 ± 226 ng Nm–3, respectively. The operating parameters significantly influenced the patterns of PAH concentration profiles. Decreasing with increasing methanol flowrate and concentration or decreasing oxygen flowrate and cell temperature, the ranges of Total-PAHs and Total-BaPeq concentrations of S1 + S2 for different runs were (36.4 ± 10.9)‒(0.98 ± 0.21) µg Nm–3 and (409 ± 226)‒(98.7 ± 30.3) ng Nm–3, respectively, with corresponding emission factors from 0.07 ± 0.03 to 2.44 ± 0.52 µg g-electrode–1 and from 7.58 ± 2.32 to 47.1 ± 26.0 ng g-electrode–1, respectively. At the same operating condition, more cathode gas-phase Total-PAHs and Total-BaPeq emissions were observed for the DMFC using a HE membrane-electrode assembly (MEA) than for using an E-TEK MEA. The DMFC had the lowest performance when the cell temperature was 60°C.