This is the ostracods census data from 157 sub-samples from two marine sediment cores, JM10-10GC and JM10-12GC, from Storfjorden, Svalbard. Cores were taken in October 2010 by RV 'Jan Mayen'. JM10-10GC is 402 cm long, sampled at 5-cm intervals. JM10-12GC is 320 cm long, sampled at 4-cm intervals. The cores comprise the last 13500 years. Cores were split in two halves and one half of each core was cut up in 1 cm thick sample slices. Each sample slice at 5 cm (core JM10-10GC) and 4 cm (cores JM10-12GC) interval was wet sieved with mesh sizes of 63, 100 and 1000 μm, oven dried, and then dry sieved with mesh-size of 150 μm. The size fraction >150 μm was analyzed for the content of benthic ostracods. All species were identified to species level.