Traditionally all bulk liquid measurements have used volume as the basis of measurements. Mass is a better basis for trade but no acceptable mass flowmeter was generally available. Coriolis mass flowmeters are now increasingly being introduced into custody transfer and fiscal metering duties for many different types of fluids. National regulations will require uncertainties of 0.1% or better to meet this change in technology and philosophy. The aim of the project is to provide information to set up standardised test methods and techniques for mass flow meters. To this end, the participating laboratories will first demonstrate their basic measuring agreement using volumetric techniques. A mass flowmeter transfer standard will then be designed and constructed. This meter package will, after being submitted to appropriate tests, circulate among the participating laboratories in order to characterize the behaviour of the mass meter package, to compare the test facilities of the participating laboratories for such transfer meters and to show the capability of the different laboratory methods.