Vitamin B1 is essential to all living organisms, as thiamine diphosphate (TDP) acts as a coenzyme for many enzymes involved in central metabolic processes. However, the term vitamin B1 does not only refer to the active coenzyme TDP, but describes a family of thiamine related molecules, i.e. thiamine, thiamine monophosphate (TMP), thiamine triphosphate (TTP), adenosine thiamine diphosphate (ATDP) and adenosine thiamine triphosphate (ATTP) which differ in the number of phosphate residues and adenylyl moieties. The main aim of this study was to characterize triphosphorylated thiamine compounds in plants and the plant model, Arabidopsis thaliana. The findings of TTP, such as detection only in aerial tissues, diurnal oscillation, light induction and dependence on photosynthesis together with the generation of TTP depleted transgenic plants should help to further elucidate the role of these compounds in Arabidopsis.