Biological invasions have become one of the most intimidating environmental and economic threats of our time, as a result of the globalisation and the rise of international commerce. Alien species of insects represent one of the most abundant groups of introduced organisms in Europe, while a large number of them are associated with substantial economic burden, biodiversity loss and disturbance to ecosystem functioning. Over the last decade, citizen-science has emerged as a valuable tool for the early detection and monitoring of alien species worldwide. Alientoma – derived from “alien” and the greek word “entoma" meaning insects – aims to create a dynamic checklist and database of these organisms in Greece, where a large number of non-native insect species is currently present. The species catalogue is based on a recent scientific review of alien insect species in Greece, which was compiled after an extensive literature search, while also taking into consideration specimens from museum collections and online databases. Alientoma provides information on alien species (i.e. status, distribution, taxonomy, common names, impacts) to the public as well as the scientific community in order to inform and assist the mitigation of their adverse impacts, respectively. This project intends to promote public participation in scientific research regarding alien species, encouraging the involvement of citizen-scientists through the collection of occurrence records.