The tutorial discusses the increasing need for standardisation of thermal characterisation of LEDS and LED-based products. It goes without saying that the LED-business is growing exponentially, in fact, much faster than analysts predicted five years ago. Unfortunately, the progress in thermal characterisation has not kept pace. Manufacturers and end-users alike are crying for fair and useful thermal data, but for different reasons. The situation is becoming a serious problem for leading manufacturers who are focussing on a sustainable business for the future and are willing to publish reliable thermal data. Unfortunately, due to the lack of worldwide accepted standards a manufacturer can publish whatever he wants. It also becomes a problem for the experienced user because the thermal data that are published are often rather useless in practice when accuracy is at stake, and accuracy is needed for an educated guess of expected performance and lifetime.