Abstract The potential of high temperature liquid chromatography (HTLC) with detection by inductively coupled plasma mass spectrometry (ICP-MS) for the determination of arsenosugars in marine organisms was examined for the first time. The retention behavior of four naturally occurring dimethylarsinoylribosides was studied on a graphite column using plain water as mobile phase. An aqueous solution of pH 8, ionic strength 13.8mM and containing 2% (v/v) of methanol, along with a column temperature of 120°C and a liquid flow rate of 1.0mL/min, were selected as the optimal conditions, as they allowed the separation of the four arsenosugars in less than 18min, without any interferences due to other common arsenic species (arsenite, arsenate, dimethylarsinate, methylarsonate and arsenobetaine). The run time could be further decreased to 12min by working at 1.5mL/min, although with a 3–4 times loss of sensitivity. The procedural limits of detection were 0.03–0.04μg As/g dry mass, and the precision of the procedure ranged from 4% for arsenosugar glycerol to 18% for arsenosugar sulfate (RSD%, n=5). The developed method was applied to a number of representative biological samples, such as algae and crustaceans, providing results consistent with previous studies. In the red algae samples, the most of extracted arsenic was as arsenosugars (81–97%), mainly arsenosugar phosphate (56–94%). On the other hand, lower concentrations of these compounds were found in the crustacean, accounting for about 15% of the extracted arsenic.