To date, over 175 different molecular species have been detected in the ISM. Many of them are formed in the gas phase, but there are a growing number of species that form more efficiently on grain surfaces during the collapse of star-forming cores. UCL CHEM is a chemical model that takes into account the gas-grain interactions occurring during this collapse, with the aim of reproducing the observed abundances of molecules in star-forming regions. Since there are few observational clues about the synthesis of complex organic molecules on grains, experiments can be performed in order to collect laboratory data of interstellar relevance. My present work couples UCL CHEM with the most recent experimental results on the formation of various complex organic molecules, including methyl formate, ethylene oxide and acetaldehyde, all which have been the subject of recent astronomical interest. In addition, I will also mention experimental work on a gas-phase project involving reactions between atomic oxygen and small hydrocarbons, which may have relevance to the circumstellar envelopes of carbon stars, hot cores, etc.