This document describes two combustion methods for the determination of halogen and sulphur contents in materials by combustion in a closed system containing oxygen, and the subsequent analysis of the combustion product using different analytical techniques. These preparation procedures are: Method A - oxygen bomb combustion (calorimetric bomb); Method B -- oxygen flask combustion (Schöniger flask). Method A is applicable to solid, pasty and liquid samples containing more than 0,025 g/kg of halogen and/or sulphur content. Method B is about 10 times less sensitive. For both methods, the limit of detection depends on the element and on the determination technique used. Insoluble halides and sulphate present in the original sample or produced during the combustion step are not completely determined by these methods.