The 5th Oil Spill Identification Round Robin within the Bonn Agreement Oil Spill Identification Network of Experts (OSINET) has been organized by NCSEMC of P.R. China. SINTEF received five oil samples and has followed the draft version of CEN-TR 2v2 of August 2010 for analyses and data treatment. No final conclusions could be made from the GC analysis and GC PW-plots. Therefore, all samples were analyzed on GC/MS, and the conclusions are based on a total evaluation of the GC/MS data (visual inspection of selected ion chromatograms and treatment of normative ratios):• The spill sample from the harbour (RR2010-1) has non-match to the samples collected on the beach (RR2010-2 and RR2010-3).• The spill sample from the harbour (RR2010-1) has non-match to the oils from the suspected sources (RR2010-4 and RR2010-5).• The sample collected on the beach in June (RR2010-2) has positive match to the sample collected in July (RR2010-3).• The samples from the beach (RR2010-2 and RR2010-3) have positive match to the oil from pipeline 1 (RR2010-4), and non-match to the oil from pipeline 2 (RR2010-5). • The oil from pipeline 1 (RR2010-4) has non-match to the oil from pipeline 2 (RR2010-5).