A tri-generation power-heat-chilling hybrid energy system based on natural gas-fed Solid Oxide Fuel Cells is simulated and analysed in size range of 250 kWe. The system consists of a partial pre-reformer reactor, a SOFC stack, a combustor, a gas turbine expander, two compressors, two recuperators and a double effect absorption chilling system based on LiBr/H2O solution. The SOFC is simulated with a zero dimensional model i.e. considering equilibrium of chemical reactions in the SOFC exit. All significant system efficiency losses were taken into account. The proposed system is examined for its electrical and thermal efficiencies characteristics in steady state design point operation. In all cases the turbine inlet temperature was kept bellow 1173 K. Electrical efficiencies of about 60% are possible having a pressure ratio 4. Overall electricity & heat/chill efficiency can reach up to 85%. An economic evaluation of such a system installed in a Greek office building is presented. A potential reduction of the electricity price up to 7% is estimated for the specific application by employing tri-generation.