The process of manufacturing cumene from propylene and benzene on a solid phosphoric acid catalyst was studied. The aim of this article is to optimize this process economically and to realize how statistical methods can be utilized to optimize the operational conditions of the process at the industrial scale. The net present value (NPV) that reflects all the economic aspects of the process was chosen as the objective function for optimization. The NPV of the base process was estimated at $0.19 million. In the first step, the full factorial design was applied to determine the significant factors affecting the process. Results revealed that benzene recycle, reactor volume, reactor pressure, and inlet temperature, as well as the binary interaction of recycle-temperature and recycle-pressure influence the NPV. Benzene recycle and inlet temperature had the most important effects on NPV. In the second step, the response surface methodology was applied to find a reliable quadratic model for NPV. Optimization of the effective parameters was carried out. The maximum predicted value of NPV was calculated $4.56 million at benzene recycle of 141.4 kmol/h, temperature of 340 degrees C, and pressure of 29 bar with 468 tubes inside the reactor.