In kernel development, water relations are known to play a key role in the control of grain-filling duration. The moment when maximum water content is attained defines the duration by determining the timing when kernels reach the critical moisture content at which biomass accumulation stops. However, recent results in sorghum have shown that the pattern in which water content in the kernel is replaced by biomass accumulation after maximum water content is reached can also affect the timing when this critical moisture content is reached. Our objective was to test if genotypic differences in maize grain-filling duration were related to differences in the moment when maximum water content was attained or in the kernel desiccation pattern during late grain filling. We also tested genotypic differences in the capacity to generate kernel volume late in kernel development. Twelve commercial hybrids were evaluated, and kernel weight, kernel water content and kernel volume were measured. In order to address differences in kernel desiccation, we calculated a ratio between the kernel water content and the dry matter accumulated from maximum water content to physiological maturity. Genotypes showed no difference in the moment when maximum water content was reached nor when the maximum kernel volume was attained; maximum kernel volume was always achieved later in development when compared to the maximum water content. Genotypic differences in grain-filling duration (p<0.001) were associated with the variation in the calculated ratio (r2=0.61; p<0.001), showing that the kernel desiccation pattern during late grain filling affected maize grain-filling duration. Differences in the desiccation ratio were related to differences in the capacity to generate kernel volume after maximum water content was reached (r2=0.36; p<0.05), suggesting that the capacity of the kernels to continue expanding during late grain filling might be playing a key role in maize grain-filling duration.