Wetting properties and capillary parameters are of first interest for composite and especially biocomposite manufacturing, interface compatibility between reinforcement and matrix, and durability. Few studies have been dedicated in literature to continuous textile fibers and uncured liquid resins wetting properties, and particularly the methods used may be ambiguous, revealing a wide dispersion in results. In this work a reliable method is proposed to determine properly the wetting properties of fibers and some resins commonly used for composite applications. Firstly, a procedure to characterize dispersive and polar components of surface tension for an epoxy and a partially bio-based resin with a tensiometer is proposed. Then a new method was applied on single fibers of semi-synthetic cellulose (viscose), which allows deriving representative values of contact angles from a series of measurements, minimizing the measurement scatter even when using a conventional tensiometer. Resin components and contact angles between cellulose fibers and test liquids, including resins, led to characterize dispersive and polar components of fiber surface energy.