Optical remote sensing in the Arctic is highly restricted by frequent cloud cover and low illumination angles, which decreases the amount of useable images during the short vegetation period considerably. As a result, even the more than 30-year long and continuous Landsat mission archive only contains few suitable images for a summer season per year. With the start of the ESA Copernicus Sentinel-2 mission in 2015 and enhanced data availability from its two satellites (S-2A, S-2B) the revisit time, combining data of the two Sentinel-2 and the Landsat-8 satellites, is shortened to less than five days in high latitude regions. The dramatic increase in the number of images per summer season enhances the likelihood for cloud-free image acquisitions considerably. The substantial increase in available multispectral satellite images for the Arctic facilitates the possibility of creating dense time series, which improve mapping vegetation and biomass and monitoring their changes in a rapidly warming Arctic. A key advantage is the capability to detect landscape dynamics and to differentiate between rapid and gradual changes, therefore describing permafrost region disturbances better and conducting trend analysis based on the time series (Nitze and Grosse, 2016). However, for a combined application of data from different sensors in time series analysis of multispectral properties, it is particularly important to assess the spectral compatibility of multispectral Landsat-8 and Sentinel-2 images. In general, the multispectral properties of Landsat-8 Operational Land Imager (OLI) and the Sentinel-2 Multispectral Imager (MSI) sensors are comparable: they feature several roughly corresponding bands and similar spatial resolutions. While both global and regional assessments of Landsat-8 and Sentinel-2 datasets already describe the combination of the two data sources, these studies also underline the necessity of regional studies to capture the landscape specific responses of both sensors before any combined application. The National Aeronautics and Space Administration (NASA) developed globally applicable adjustment equations per band from Sentinel-2 to Landsat-8 (Claverie et al., 2016). For Arctic permafrost regions a detailed comparison has not been facilitated so far. Therefore, it will be of interest whether this linear adjustment is sufficient for Arctic areas or whether it has to be modified. The aim of this study in progress is to assess spectral characteristics of Landsat-8 and Sentinel-2 same-day acquisition images from summer 2016 for three sites: the Arctic central Lena Delta, Batagay in the Yana Highlands and Yukechi in central Yakutia. These three sites are located along an approximate longitudinal transect and exemplify the different climatic, geologic, geomorphologic and vegetational conditions of the heterogeneous North Eastern Siberian permafrost landscapes. We assess image pairs corrected to surface reflectance and cloud masked based on single band comparisons, multispectral indices (e.g. normalized difference vegetation index (NDVI)) and the sensor responses over a summer period. While we hypothesize that both sensors show the same spectral properties, we expect that the specific signal responses may differ systematically. Therefore, in certain analysis contexts, the joint use of Landsat-8 and Sentinel-2 imagery requires the application of spectral adjustment. The analysis of the three study sites and their variety of land cover characteristics will likely indicate the range of differing signal of Landsat-8 and Sentinel-2 images and help defining an applicable adjustment scheme for the Arctic.