After World War II ended in 1945, Bruno Tesch and Karl Weinbacher of Tesch & Stabenow were tried in a British military court and executed for knowingly providing Zyklon B to the SS for use on humans. Gerhard Peters, who served as principal operating officer of Degesch and Heli and also held posts in the Nazi government, served two years and eight months in prison as an accessory before being released due to amendments to the penal code.
Use of hydrogen cyanide as a pesticide or cleaner has been banned or restricted in some countries. Most hydrogen cyanide is used in industrial processes, made by companies in Germany, Japan, the Netherlands and the US. Degesch resumed production of Zyklon B after the war. The product was sold as Cyanosil in Germany and Zyklon in other countries. It was still produced as of 2008. Degussa sold Degesch to Detia-Freyberg GmbH in 1986. The company is now called Detia-Degesch. Up until around 2015, a fumigation product similar to Zyklon B was in production by Lučební závody Draslovka of the Czech Republic, under the trade name Uragan D2. Uragan means "hurricane" or "cyclone" in Czech.
Subsequent use of the word "Zyklon" in trade names has prompted angry reactions in English-speaking countries. The name "Zyklon" on portable roller coasters made since 1965 by Pinfari provoked protests among Jewish groups in the U.S. in 1993 and 1999. In 2002, British sportswear and football equipment supplier Umbro issued an apology and stopped using the name "Zyklon", which had appeared since 1999 on the box for one of its trainers, after receiving complaints from the Simon Wiesenthal Center and the Beth Shalom Holocaust Centre. Also in 2002, Siemens withdrew its application for an American trademark of the word "Zyklon", which their subsidiary BSH Bosch und Siemens Hausgeräte had proposed to use for a new line of home appliances in the United States. (The firm was already using the name in Germany for one of their vacuum cleaners.) Protests were lodged by the Simon Wiesenthal Center after the trademark application was reported to BBC News Online by one of their readers. French company IPC's product names used "Cyclone" for degreasers and suffix "B" for biodegradable: "Cyclone B" was renamed  ("green cap") in 2013 after protests from Jewish groups. A rabbi said the name was "horrible ignorance at best, and a Guinness record in evil and cynicism if the company did know the history of the name of its product."
Holocaust deniers claim that Zyklon B gas was not used in the gas chambers, relying for evidence on the discredited research of Fred A. Leuchter, who found low levels of Prussian blue in samples of the gas chamber walls and ceilings. Leuchter attributed its presence to general delousing of the buildings. Leuchters negative control, a sample of gasket material taken from a different camp building, had no cyanide residue. In 1999, James Roth, the chemist who had analyzed Leuchters samples, stated that the test was flawed because the material that was sent for testing included large chunks, and the chemical would only be within 10 microns of the surface. The surface that had been exposed to the chemical was not identified, and the large size of the specimens meant that any chemical present was diluted by an undeterminable amount. In 1994, the Institute for Forensic Research in Kraków re-examined Leuchter's claim, stating that formation of Prussian blue by exposure of bricks to cyanide is not a highly probable reaction. Using microdiffusion techniques, they tested 22 samples from the gas chambers and delousing chambers (as positive controls) and living quarters (as negative controls). They found cyanide residue in both the delousing chambers and the gas chambers but none in the living quarters.