In the present study an ACO algorithm is adopted as a part of a document classification system that classifies documents written in Greek, in thematic categories. The main purpose of the ACO module is to create a word map that will assist in the representation of the documents in the pattern space. The word map creation algorithm proposed involves additional deterministic sub-routines and aims at clustering together into groups thematically-related words. The performance of the proposed system is compared with an alternative system implementation that is based on the established SOM neural network.