The gas discharge plasma has attracted the attention of scientists and technologists because it is a source of electrons and ions beams which are needed and used in several applications and modern instruments. Minimum breakdown voltage of the cylindrical coaxial virtual cathode oscillator is investigated on Nitrogen (N2), Argon (Ar), Helium (He) and Hydrogen (H2) through different anode transparencies. The study includes the effect of secondary electron emission on the minimum breakdown voltage (Vb)min and the product of gas pressure P and inter-electrode distance d, Pdmin. The changes in the minimum breakdown voltage with the gas pressure are studied where pressure is the main factor of electric discharge. Paschen curve is studied through electric discharge for Ar and H2 by using different anode transparencies. This study aims to understand the parameters that can affect the minimum voltage (Vb)min at which the gas transfers from a non-conducting state to a conducting state. The study is carried out on a cylindrical coaxial vircator for different gases and different anode transparencies.