In the In Your Element article 'First there was hydrogen' (Nature Chem. 7, 264; 2015), the image was incorrect and did not depict a hydrogen balloon. The sentence referring to the image should have read 'Molecular H2 filled one of the first balloons used to carry people in 1783 (pictured), and the fuel tanks of rockets two centuries later, permitting the inquisitive to explore further and further.' These errors have been corrected in the online versions after print: 18 March 2015.