Iguanodon suessii was named by Bunzel (1871). Its type specimen is PIUW 2349, a mandible (right dentary), and it is a 3D body fossil. Its type locality is Muthmannsdorf, which is in a Campanian estuary/bay coal/sandstone in the Grünbach Formation of Austria.

It was recombined as Mochlodon suessii by Seeley (1881), Dollo (1882), Sauvage (1882), Gaudry (1890) and Nopcsa (1902); it was synonymized subjectively with Rhabdodon priscum by Nopcsa (1915), Nopcsa (1915), Nopcsa (1923) and Huene (1927); it was recombined as Rhabdodon suessi by Kuhn (1964) and Galton (2009); it was recombined as Rhabdodon suessii by McIntosh (1981); it was synonymized subjectively with Rhabdodon priscus by Brinkmann (1988), Norman and Weishampel (1990) and Norman (2004); it was misspelled as Mochlodon suessi by Nopcsa (1900); it was considered a nomen dubium by Sachs and Hornung (2006); it was recombined as Mochlodon suessi by Zittel (1890), Nopcsa (1901), Mamulea (1953), Weishampel and Weishampel (1983), Rich et al. (1983), Osi et al. (2012), Dieudonné et al. (2016), Bell et al. (2018), Madzia et al. (2018) and Herne et al. (2019).