Besides composing, he conducts the Netherlands Police Band, the Philips Symphonic Band and several Dutch community bands, teaches at international courses and guest conducts.
Hardy Mertens also teaches band conducting at the Tilburg Conservatory.
Compositions by Hardy Mertens are rooted in the European orchestral tradition and often influenced by folk music from different continents. Traditional tonality, extended melody lines and percussive patterns are often combined with humorous surprises and unusual sounds. This complexity usually results in a high grade of difficulty and sometimes this causes controversy with conductors and musicians.