There are many methods and instruments available for powder characterization and they are more or less well suited to powders in different size ranges. This report presents in more detail the relatively recent Centrifugal Particle Sizer (CPS) and its potential for particle size distribution measurement compared to more classical techniques (microscopy, laser diffraction, or photo correlation spectroscopy). To get reliable comparable data is of primary importance for new application developments. A series of protocols for nanosized powders - nanopowder metrology - was produced within the framework of a COST Action - COST 539 “Electroceramics from Nanopowders Produced by Non-conventional Methods”. The protocols have been tested using well-characterized commercial products, and for a series of powders produced in the COST Action 539. The results show that results between methods and or laboratories are often very good but some show significant deviations illustrating the need for a systematic approach and how the protocols can help us develop a Nanometrology for new functional powders.