Due to his remarkable inventiveness in dissonant chords, Walter Horn may be described as a master of discords.

His first piano compositions were written as early as 1939, followed by further pieces in late romantic style, which were composed during his stay at the military hospital in Bad Pyrmont in 1946.

From 1952 to 1962 Walter Horn lived in Köln-Vingst as a lodger. At that time he had no piano, which explains why he wrote only few compositions then. Later in his early 40s Walter Horn had time again for his compositions developing his modern piano style. During the 1960s, in the course of which serial music was booming, he restrained himself. He didn't want to completely break with traditions, and above all, he refused to quit writing melodies. Any kind of music that was there had a strong influence on him.

As a rule, his pieces consist of two parts. An initial theme is introduced, processed thematically, followed by a second theme, and at the end of the composition these two themes are combined. Walter Horn never wrote simple pieces. Even in his shorter compositions he preferred wide-set chords and large leaps of the chords. He was particularly fond of complicated rhythms, change of times, change of tempi, and fifth intervals. The listening example - Piece for Piano C major, 1999 - can be regarded as one of Walter Horn's simplest pieces.

In the late 1980s Walter Horn had so many musical ideas that he – possibly due to lack of time – discontinued setting expression marks in his scores.

During the last years in his life, Walter Horn summarized his earlier compositions into series, but he only got as far as opus 16. He had great fun doing that, knowing, however, that his early works were of no musical value anymore.

Of special interest might be his dedications opus 8. Here Walter Horn presented his musical interpretations of the characters of his family members and friends: His wife Dietlinde, his father Leonhard, his mother Sophie, his son Michael, his daughter Heike, his sister Ilse, his brother-in-law Roland, his mother-in-law Gertrud, and his father-in-law Emil.

Other than that, he gave no descriptions to his pieces, always referring to the three stars of R. Schumann.

Composing was Walter Horn's passion. He never had any creative crises and always lots of musical ideas. He admitted, however, that there had been a split of the pen every now and then, and stated that he had no appreciation for some of his earlier works anymore. Apart from that, composing always came very easily to him, although earlier pieces were corrected and improved from time to time.

It will take further years or even decades until Walter Horn's musical works can be entirely looked through and evaluated.