The objectives of this research were to understand the process of converting toluene into phenol in a one-step process directly from a water–toluene mixture using the plasma in-liquid method.Experiments were conducted using 27.12 MHz radio frequency(RF) in-liquid plasma to decompose a solution of 30% toluene. Based on the experimental results as evaluated using gas chromatography–mass spectrometry(GC–MS), along with additional analysis by the Gaussian calculation, density functional theory(DFT) hybrid exchange–correlational functional(B3LYP)and 6-311 G basis, the phenol generated from toluene was quantified including any by-products.In the experiment, it was found that OH radicals from water molecules produced using RF inliquid plasma play a significant role in the chemical reaction with toluene. The experimental results suggest that phenol can be directly produced from a water–toluene mixture. The maximum phenol yields were 0.0013% and 0.0038% for irradiation times of 30s and 60s,respectively, at 120 W. The objectives of this research were to understand the process of converting toluene into phenol in one-step process directly from a water-toluene mixture using the plasma in-liquid method. Experiments were conducted using 27.12 MHz radio frequency (RF) in-liquid Based on the experimental results as evaluated using gas chromatography-mass spectrometry (GC-MS), along with additional analysis by the Gaussian calculation, density functional theory (DFT) hybrid exchange-correlational functional ( B3LYP) and 6-311 G basis, the phenol generated from toluene was quantified including any by-products. In the experiment, it was found that OH radicals from water molecules produced using RF in liquid plasma play a significant role in the chemical reaction with toluene The experimental results suggest that phenol can be directly produced from a water-toluene mixture. The maximum phenol yields were 0.0013% and 0.0038% for irradiation times of 30s an d 60s, respectively, at 120 W.