Abstract: Experiments that revealed the main trends in the development of complete breakdown in a long capillary tube for different electrode configurations are reported. It is demonstrated that, in the presence of an additional external electrode around the tube, a fast stage completing the breakdown is preceded by a slow stage caused by development of a weak-current surface barrier discharge inside the tube. This discharge is realized due to propagation of forward (from the high-voltage electrode) and backward (from the grounded electrode) surface ionization waves. The presence of preliminarily, locally deposited charge of the sign opposite to polarity of the voltage pulse leads to acceleration of propagation of ionization waves in the tube. In the absence of the external electrode, the breakdown occurs much faster but is characterized by a large scatter in the delay time (up to complete lack of breakdown) relative to the applied voltage pulse. Unstable operation of the gas-discharge device determined by development of breakdown represents a much more serious problem in many applications compared to the situation in which it turns on slowly but stably. Therefore, the results demonstrating the possibility of controlling the breakdown are of great scientific and practical value.