Bone is one of the most widely used materials for dating archaeological activity. It is also relatively difficult to pretreat effectively and new methods are an area of active research. The purpose of the chemical pretreatment of bone is to remove contaminants present from burial and to do so in a way which does not add any additional laboratory contaminant. To some extent, these two aims must be balanced since, on the whole, the more complex the procedure and the more steps included, the greater the chance for contamination. At the Oxford Radiocarbon Accelerator Unit (ORAU), the method used is a continuous-flow or manual acid/base/acid (ABA) treatment followed by gelatinization and ultrafiltration (based on Brown et al. ; documented in Bronk Ramsey et al. ). We find this overall method is very effective at removing more recent contamination in old bones. However, two aspects of the method have recently been improved and are reported here: the redesign of ORAU's continuous flow pretreatment and a new protocol in our pretreatment ultrafiltration stage.