In summer 1935, Heinz Gengler founded the First Accordion Orchestra of Cologne. He has been the Orchestra's conductor since its inception. The orchestra is the oldest and one of best known in the area between  "Main River" and  "North Sea". The ensemble gave its first public concert only three months after foundation. Regular concerts at the Academy of Music Cologne (the Cologne Conservatory of Music, before its destruction during World War II) led to widespread popularity, and the Orchestra quickly gained a leading position in folk music in the Rhineland.

In the early days, the First Accordion Orchestra of Cologne performed music by composers such as Haag, Hermann, Mahr and Zilcher, as well as Hermann Unger. The audiences greatly appreciated songs by these composers, and they continue to be part of the Orchestra's main repertoire. Broadcasts by Radio Cologne contributed greatly to its early popularity.

In 1944, the ensemble was forced to dissolve. In 1955 Heinz Gengler came back to Cologne - his favourite town - , and  the orchestra came together again and began to give regular rehearsals.
Only three months later and with merely 10 musicians, the orchestra was ready to perform again. Within a short time, the number of members reached 40-45, and this remained constant since then.

Due to the unrelenting efforts by Heinz Gengler several youth orchestras have been created to ensure that young people have the opportunity to be trained and gain experience as musicians. The "Main Orchestra", the "Youth Orchestra", the "Accordion-Youngsters" and the "Children's Group" are four groups with more than 90 players.

Frequent performances in Belgium, Denmark, France, the United Kingdom, Italy, Australia, the Netherlands, Liechtenstein, Switzerland and Germany have received critical acclaim, contributing to the popularity of the Orchestra both at home and abroad. Visits to the United States of America in 1967, and to South Africa and Namibia in 1969 were among the greatest artistic challenges. Other musical highlights were concert tours to Prague, Warsaw, Vilnius and Kaunas/Lithuania, Daugavpils/Latvia, St. Petersburg in 1991. There was a third and fourth overseas tour to Brazil in 1997 and Canada in 1999.

The Cologne Accordion Orchestra has always received  excellent reviews at national and international music competitions.

Along with others, a special task of the Orchestra is to take care of our common musical heritage. The Orchestra represented the German Harmonica Association during the presentation of the "Zelter-Plakette" award by the President of the German Government.

The First Accordion Orchestra Cologne has a varied repertoire of more than 200 pieces of music, fitting different musical tastes and expectations. More than 70 pieces have been produced in collaboration with the "Westdeutscher Rundfunk" (WDR), Germany's public broadcasting corporation.