The present invention concerns an encoding method in which encoding is performed of any information word a of length k in the form of a word .nu. belonging to a Reed-Solomon code C of dimension k' and length n' (with n'-k'=n-k) such that the components of .nu.' situated in (n'-n) arbitrary predetermined positions be systematically equal to respective predetermined constants (for example, all zero). The possibility then exists of deleting those components of fixed value to obtain a word .nu. of length n belonging to a code C, which thus constitutes a code that is shortened with respect to code C. The invention also relates to devices and apparatuses adapted to implement the encoding method. The invention may be used for encoding by means of an algebraic geometric code, when such encoding may be implemented by encoding by means of a plurality of shortened Reed-Solomon codes.