Abstract: It has been discovered that vortex flowmeters can be suitably adapted for the measurement of two-phase fluid flows, and particularly for the measurement of steam quality, when disposed in a particular manner in horizontal flowpipes carrying such fluids. More specifically, the invention disclosed includes the disposition of a substantially linear vortex flowmeter horizontally and transversely in a horizontal flowpipe to measure two-phase fluid flows, for example, wet steam quality. When the mass flow rate is not determinable through knowledge of the feedstock, other sensors enable measurement of the vapor phase volumetric area and velocity to permit calculation of the flow measurand.