Capillary adhesion has been pointed out to be an important mechanism controlling the properties and behaviour of medium-particle-size dispersed material. A generalised method for calculation meniscus curvature radii of liquid bridge formed between powder particles as a result of water vapour condensation has been given. The obtained relationships will be a basis for capillary adhesion force calculations and for estimation of the effect of relative humidity of surrounding atmosphere on the forces. A complete analysis of the meniscus radii has been accomplished for all important contact configuration systems existing in powders. On this basis hypotheses concerning the values and trends of adhesion forces in powders have been proposed.