Low and high molecular weight hydrogenated starch hydrolysates (HSH) were added to amorphous isomalt and lactitol, and the glass transition temperature (T_g) and crystallisation behaviour was monitored during storage at 80% relative humidity. Prior to storage, only one T_g was detected in all the binary mixtures when scanned in the differential scanning calorimetry and the T_g was in the temperature range between the T_g of the individual components. When the amorphous samples were stored in humid conditions, more than one T_g were detected. The T_g at the lowest temperature rapidly decreased during storage as the moisture uptake increased but then stabilised at approximately -40°C. The maximum moisture uptake of the samples was 40% (w/w) and resulted in the formation of a transparent viscous solution. Eventually crystallisation was observed. It was found that both the low and the high molecular weight HSH reduced the crystallisation of isomalt, but the low molecular HSH was the most effective.