Dimethylsulphoniopropionate (DMSP) is acknowledged to be found in different sea-ice environments in concentrations several orders of magnitude higher than in the open ocean. Dimethylsulphoxide (DMSO), which can act either as a source or a sink towards dimethylsulphide (DMS), is reported to often be the dominant dimethylated sulphur species in the marine environment. Studies reporting occurrence of DMSO in the sea-ice environment are, however, scarce or even nonexistent with regard to Antarctic sea ice. In this study we present the temporal evolution at high resolution of DMSO concentration in the ice cover of two contrasting sites of the ice station ‘Belgica’ (SIMBA cruise, Bellingshausen Sea, September–October 2007). ‘Brussels’ site was characterized by mostly columnar thin ice and thin snow cover while ‘Liege’ site showed mostly granular thick ice and thick snow cover. Multiple cooling and warming cycles induced major thermodynamic shifts within the sea-ice cover during the observation period as attested by the main physical parameters (texture, temperature, bulk and brines salinity, relative brine volume) studied. At Brussels site, DMSO ranged between 5 nM and 767 nM, and between 1 nM and 219 nM at Liege site. At both sites, most of the changes in concentration were observed in the top 20 cm of the ice cover where the main changes in ice temperature and salinity were also recorded. Contrarily to the water column where DMSO is often the dominant dimethylated sulphur compound, DMSO showed at all times the lowest concentration amongst all the dimethylated sulphur species (DMS, DMSP, DMSO) measured in the ice. DMSO contribution to the total DMS, DMSP and DMSO pool ranged between 2% and 7% along the study period at the two sites. Relationships of DMSO with a full set of physical (texture, temperature, bulk and brines salinity, relative brine volume, susceptibility to brine drainage), biological (chlorophyll a, autotrophic biomass composition) and biogeochemical (DMS, DMSP) data will be investigated in order to highlight the main factors controlling the dynamics of DMSO in sea ice in a context of major shifts in the thermodynamics of the sea-ice cover.