<b>Abstract</b>— <p>Based on passive microwave remote sensing data, the dynamics of the area of sea ice and ice-free period (IFP) parameters in the East Siberian Sea were analyzed. The average annual start and end dates, as well as the duration of the IFP and rates of their changes for the period 1979–2022, were calculated. Also the features of the spatial and temporal distribution of the IFP parameters were described in the western and eastern parts, as well as in the entire water area, of the East Siberian Sea. From August to October, there is a significant decline in area of sea ice in the East Siberian Sea. This reduction has led to an increase in the duration of IFP. It is shown that during 1979–2022, the duration of he IFP in the East Siberian Sea increased statistically significantly by only 45% of the water area, mainly in the sea’s southern regions. The average rate of increase in the duration of the IFP is estimated as 15 ± 4 days/decade. The increase in the IFP duration is due to both a statistically significant shift in the IFP start dates towards earlier dates (occurring in 33% of the water area) and a statistically significant shift in the IFP end dates towards later dates (occurring in 59% of the water area). The average rates of change in the start and end dates of the IFP are similar in magnitude (8&#xa0;±&#xa0;3 days/decade), but differ in direction: negative for start dates and positive for end dates. Spatial patterns changes in IFP start dates have a greater impact on changes in the duration of the IFP in the western East Siberian Sea, while changes in IFP end dates have more of an influence on changes in the duration of the IFP in the eastern part of the sea.</p>