Abstract:The cataluminescence (CTL) of benzene and the benzene homologues toluene and xylene on nanosized γ-Al 2 O 3 doped with Eu 2 O 3 (γ-Al 2 O 3 /Eu 2 O 3 ) was studied and a sensor of determining these gases was designed. The proposed sensor showed high sensitivity and selectivity at an optimal temperature of 432 ºC, a wavelength of 425 nm and a flow rate of 400 mL/min. Quantitative analysis was performed at the optimal conditions. The linear ranges of CTL intensity versus concentration of the benzene homologues were as follows: benzene 2.4~5000 mL/m 3 , toluene 4.0~5000 mL/m 3 and xylene 6.8~5000 mL/m 3 , with detection limits (3σ) of 1.8 mL/m 3 , 3.0 mL/m 3 and 3.4 mL/m 3 for each one, respectively. The response time of this system was less than 3 s. The coexistence of other gases, such as SO 2, CO and NH 3, caused interference at levels around 11.7%, 5.8% and 8.9% respectively. The technique is a convenient and fast way of determining the vapors of benzene homologues in air.