A high step-up gain DC-DC converter is proposed on this work based on the stacking of three conventional buck boost dc-dc converters. The principle of operation, statics analysis and simulation results are included in this paper. A laboratory prototype of the proposed converter has been designed and implemented in order to test and verify experimentally, with rated power of 1 kW, 100 V input voltage, 400 V output voltage, 50 kHz switching frequency. The tested results serve to verifier both the operational principle and the quantitative analysis. Beside operation with high static gain, the voltage across the power semiconductors is half of the output voltage, that contributes to reduction of the both conduction and commutation loss.