In the electroplating industry, it is essential to know and control the current density distribution in the electroplating cell. To make clear the behaviour of gas bubbles produced in the horizontal electroplating cell, the effects of the electrolyte velocity and average current density on the current density distribution in the cell were investigated. The increase in overall resistance and the resulting non-uniformity in current density distribution in the horizontal electrolysis cell were theoretically discussed by modifying Tobias concept derived for the vertical electrolysis cell.