•Parent material is the main forming factor for soil differentiation at Vega Island.•Vega Island is a pedological transition zone between Maritime and Continental Antarctica.•Salinization, desert pavement formation and cryoturbation mark the transition.•Sulfurization is the main pedogenic process responsible for chemical changes.•Despite the semiarid climate, pedogenesis is very active in the soils of Vega Island. Vega Island in the Weddell Sea is characterized by a semiarid climate and peculiar soil formation due to its transitional location between warmer and wetter Maritime Antarctica (MA) and drier colder Continental Antarctica (CA). We investigated the main factors and processes involved in soil genesis at Cape Lamb on Vega Island. Thirty pedons were sampled, described and analyzed for morphological, physical, geochemical and mineralogical properties. Twenty-two pedons were classified as Gelisols/Cryosols. Three soil groups were identified: (1) mixed substrates soils (2), acid sulfate soils and (3) basaltic soils. Acid sulfate soils showed the greatest degree of weathering with pronounced acidity due to sulfurization. Basaltic soils were the least developed and presented shallow pedons of skeletic character and high alkalinity. Parent material was the main factor in the differentiation of the studied soils. Climate and landforms were also important. Desert pavement, salinization and ahumic features induced by the semiarid climate, oppose acidification and cryoturbation, characterizing the transitional location of Vega Island. Patterned ground dominates on periglacial highlands, while desert pavements are more common on paraglacial surfaces. Despite the semiarid climate, pedogenesis is active in the studied soils, with clay minerals, sulfate minerals and pedogenic Fe-oxides formation.