Abstract: A bi-directional flow impulse type turbine arrangement (120) for use with a bi-directional reversing flow (F, F1, F2), and in particular for use with an oscillating water column power plant (110). The turbine arrangement (120) has a rotor (120), and first and second sets of guide vanes (140, 142) located on an opposite axial sides of the rotor (132) for directing the bi-directional reversing flow (F, F1, F2) to and from the rotor (132). The guide vanes (140, 142) are disposed at a greater radius and radially offset from the rotor blades (136). The turbine arrangement further comprises first and second annular ducts disposed respectively between the first and second sets of guide vanes (140, 142) and the rotor (132) for directing fluid from the guide vanes (140, 142) to the rotor blades (136).