This paper presents an evaluation of the influence of relative humidity and temperature on the flowability of the following food powders: flour, tea and whey permeate. These powders were selected because of their different physical properties. Powder flowability was measured using an annular shear cell in a chamber with controlled relative humidity and temperature. A number of powder physical properties, including particle size distribution, water sorption isotherms and differential scanning calorimetry (DSC) thermograms, were measured. These properties are used in interpreting and comparing the flowability measurements for each powder.