High step-up ratio DC-DC converters for low-voltage high-current energy sources are nowadays the focus of an intensive research activity, thanks to the increasing interest for renewable energy sources like those based on photovoltaic panels and fuel-cells. One class of these high gain converter topologies combines a boost input stage with a voltage multiplier cell, to step-up the output voltage beyond the boost capability. The aim of this paper is to derive the small-signal model of the Interleaved Boost with Voltage Multiplier (IBVM), whose operation was described in [18]–[19]. The classical state-space averaging approach has been employed together with considerations on waveform symmetry. A reduced order model is also derived showing that, with ideal lossless components, the control-to-output voltage dynamics is identical to that of a standard boost converter having twice the inductance. The derived model is validated by simulations and by experimental measurements taken on a 1kW rated converter prototype that boosts a 24V battery voltage to 400V.