Geometrical characteristics of a reactor for the synthesis of terephthalic acid via the liquid-phase oxidation of p-xylene with air oxygen in the presence of a multicomponent (Co + Mn + Br) catalyst, the type and design of a stirring device, and reactant feed sites that ensure the maximal p-xylene conversion and the minimal impurity content in the oxidate were determined by mathematical simulation methods and are recommended for use. Optimal (basic) process control parameters for the terephthalic acid synthesis reactor with an annual capacity of 250000 t were also determined and recommended. A comparative analysis of the calculation results and experimental data on the influence of the process control parameters on the product quality (impurity content, color, transparency) was performed.