In 1967, Kroto began teaching and research at the University of Sussex in England.  During his time at Sussex from 1967 to 1985, he carried out research mainly focused on the spectroscopic studies of new and novel unstable and semi-stable species.  This work resulted in the birth of the various fields of new chemistry involving carbon multiply bonded to second and third row elements e.g. S, Se and P. A particularly important breakthrough (with Sussex colleague John Nixon) was the creation of several new phosphorus species detected by microwave spectroscopy.  This work resulted in the birth of the field(s) of phosphaalkene and phosphaalkyne chemistry.  These species contain carbon double and triple bonded to phosphorus (C=P and C≡P) such as cyanophosphaethyne.
In 1975, he became a full professor of Chemistry. This coincided with laboratory microwave measurements with Sussex colleague David Walton on long linear carbon chain molecules, leading to radio astronomy observations with Canadian astronomers surprisingly revealing that these unusual carbonaceous species exist in relatively large abundances in interstellar space as well as the outer atmospheres of certain stars – the carbon-rich red giants.