The present invention relates to a process for preparing a mixture of cetylated fatty acids and a system for carrying out said process. Furthermore, the present invention relates to a composition comprising, or alternatively, consisting of said mixture of cetylated fatty acids. Finally, the present invention relates to said composition for use in the treatment and/or prevention of: (i) rheumatoid arthritis of inflammatory and non-inflammatory origin, in particular osteoarthritis; (ii) other inflammatory joint conditions; (iii) psoriasis, lupus, periodontal diseases or cardiovascular or heart diseases; (iv) all post-traumatic osteoarticular pathologies including sports injuries; (v) all degenerative joint pathologies (arthrosis, gonarthrosis, coxarthrosis, etc.), and (vi) inflammatory-traumatic tendon and muscular conditions. Furthermore, it is envisaged that the composition of the present invention be used in the treatment and/or prevention of the above-mentioned pathologies and disorders (i)-(vi) in association with a rehabilitative therapy. The composition comprising said mixture is formulated in a pharmaceutical form for oral use (novel food, supplement or medical device), i.e. in the form of a pill, pastille, capsule, tablet, granules, dispersible powder, syrup, solution or sprayable solution; for topical use, i.e. in the form of a cream, unguent, ointment, gel or spray to be used as such for application on the skin, or else for transdermal use in the form of a patch.