Dimethylsulphide (DMS) is a volatile sulphur compound produced among others through the degradation of dimethylsulphoniopropionate (DMSP), a metabolite synthesized by some phytoplanktonic and ice algae species to act as a cryoprotectant and osmoregulator. It is also a main component of the biogeochemical sulphur cycle and the primary source of marine-derived sulphate aerosols which play an important role in the Earth–atmosphere radiation balance. So far, very few studies have investigated the dynamics of DMS and DMSP in sea ice despite the fact that sea ice has been shown to contain considerably higher DMS and DMSP concentrations than the water column. Furthermore, sea ice is usually not considered in models as a potential source of DMS for the atmosphere which may lead to underestimations of global natural sulphur emissions. This study presents the results gathered from two cruises in both hemispheres (ARISE in the East Antarctic cruise, Australian Sector, September–October 2003 and IPY Canadian CFL study in the Beaufort Sea area, November 2007–June 2008). We measured high-resolution profiles of DMS and DMSP in ice-core samples for more than 30 stations exhibiting contrasted ice and snow conditions. We used a low temperature dry-crushing technique to extract the DMS from the ice matrix which has been proven to avoid bias related to the partial and artificial transformation of DMSP into DMS on melting. DMS concentrations were then measured using the standard purge and trap method and a GC-FPD. DMSP concentrations were also determined using the same technique through the addition of NaOH to the samples. In order to investigate the factors driving the dynamics of these compounds during both cruises, we also collected a large set of sea-ice biogeochemical properties. Together these results gave us the opportunity to depict and compare the production and behaviour of these important sulphur compounds in Arctic and Antarctic sea ice.