The aim of this paper is to reveal the influence of the photoeffect on the initial phase of the electrical breakdown. The results of a two-dimensional computer simulation of the breakdown phase in a plasma focus (PF) device are presented. The spatial and temporal developments of the electron and ion densities are calculated by solving numerically the continuity equations together with the Poisson equation. We assume that any swarm of charged particles comes almost instantaneously in dynamic equilibrium by way of various ionisation, transport and electrode processes that depend on the local value of the electric field/gas number (E/N) ratio. To reveal the influence of the photoeffect on the breakdown development process, it was assumed that electrons are emitted from the cathode as a result of positive ions bombardment and photoemission.