Electrical resistance tomography (ERT) has been chosen as the field of study because of its advantages of being low cost, suitable for various kinds and sizes of pipes and vessels, having no radiation hazard, and being non-intrusive. In the development of ERT systems for metallic bubble column, prior knowledge of the fundamental process of the ERT system whilst improving the design and operation of the process equipment is essential. The fabricated electrodes need to be electrically insulated from the metal wall. Besides that, conducting boundary strategy is implemented to overcome the grounding effect of the metallic vessel.