The safety of pressure vessels has been a concern in recent years. Old pressure vessels are susceptible to failure due to fatigue damage after several years of usage. Fire and spill of hazardous liquid or gas due to pressure vessel failure can cost human life and cause property damage. Therefore, monitoring these critical structures has become a problem of considerable interest. Nondestructive testing and structural health monitoring play an important role for both manufacturing and periodic inspection of pressure vessels. Acoustic emission technology is a popular and widely used technology for pressure vessel monitoring. The acoustic source localization (ASL) technique developed for the two-dimensional planar structures is applied to the surface of a cylindrical pressure vessel. The ASL on the cylindrical pressure vessel surface is performed by the time difference of arrival (TDOA) method without knowing the acoustic properties of the material. In the experiment six sensors are placed in two clusters. The location of the acoustic source is unknown, and the arrival time of the acoustic signal to each sensor is measured. After analyzing the measured data as discussed in the paper one can calculate the acoustic source position. The method is experimentally verified. The results show that the above technique can quickly and accurately locate the acoustic source position on the surface of a cylindrical pressure vessel without having the complete knowledge of the structural properties of the material.