Due to the large energy potential of biofuel production, in the near future the construction of new biogas plants in Poland is expected. However, prior to any investment in the biogas market it is necessary to conduct performance tests of methane production from the used substrates and to perform simulation of the initial start-up on a laboratory scale. The start-up of agricultural biogas plants on a laboratory scale is simulated using pig slurry and maize silage. In this lab-scale simulation, the same conditions of running are created as for real-scale biogas installation. The research tests prove the suitability of advanced continuous stirring-tank reactors (CSTRs) to optimize the operation of biogas installations on a real scale.