To support the industrial design and process development for the separation of xylenol isomers from coal tar, the present work was focused on 2,4/2,5-xylenol mixture as 2,4-xylenol and 2,5-xylenol have very close boiling points. Specifically, the kinetics of the alkylation of 2,4/2,5-xylenol mixture was investigated that formed the first step of the alkylation-distillation-dealkylation separation strategy. By quantifying the influence of various key factors on the reaction rate, the rate equations of 2,4-xylenol and 2,5-xylenol alkylation were determined as $${{r}_{{2,4}}} = 1538{{e}^{{{{ - 39{\kern 1pt} 360} \mathord{\left/ {\vphantom {{ - 39{\kern 1pt} 360} {RT}}} \right. \kern-0em} {RT}}}}}c_{{2,4}}^{{1.1}}P_{{{\text{PIB}}}}^{{1.0}}c_{{{\text{PTSA}}}}^{{0.4}}$$ and $${{r}_{{2,5}}} = 516{{e}^{{{{ - 32{\kern 1pt} 241} \mathord{\left/ {\vphantom {{ - 32{\kern 1pt} 241} {RT}}} \right. \kern-0em} {RT}}}}}c_{{2,5}}^{{1.0}}P_{{{\text{PIB}}}}^{{0.8}}c_{{{\text{PTSA}}}}^{{0.7}}{\text{,}}$$ respectively. The alkylation rate of 2,4-xylenol was notably higher than that of 2,5-xylenol. The influence of temperature, xylenol concentration and isobutylene partial pressure on the reaction rate of 2,4-xylenol was also greater than that of 2,5-xylenol, whilst the influence of catalyst dosage on the alkylation rate of 2,5-xylenol was found to be greater than that of 2,4-xylenol. The results can be potentially used for reactor design and process development for the separation of 2,4/2,5-xylenol mixture from coal tar.