Journal of Digital Information Management Julian Szymanski 10 6 2012 http://dline.info/fpaper/jdim/v10i6/5.pdf In the article we describe the approach to parallel implementation of elementary operations for textual data categorization. In the experiments we evaluate parallel computations of similarity matrices and k-means algorithm. The test datasets have been prepared as graphs created from Wikipedia articles related with links. W also present the approach to computing pairs of eigenvectors and eigenvalues for visualizations of the datasets. The implemented basic operations: computing similarity matrix, data clustering and spectral analysis have been used in our system for visualization of the Wikipedia categories on SOM as well as in a system for categorization search results in Wikipedia.