Applications of surface classifications have included the detection and assessment of hazardous glacial lakes [8; 9], the evaluation of ice avalanche potential in periglacial and glacial environments [10] or delimiting and mapping debris-covered glacier surfaces [3; 11; 12; 13]. Developments in optical satellite remote sensing have led to a limited number of very-high resolution sensors, represented by IKONOS, QuickBird, OrbView-3, SPOT-5, Worldview 1-4, GeoEye, and the Pleiades twins. In this study, we evaluate the use of very high-resolution (VHR) tri-stereo optical imagery (0.5-m resolution of panchromatic images) from the Pleiades-1 satellite constellation for glaciological applications. We apply photogrammetric techniques to Pleiades tri-stereo data and generate a 1-m resolution DEM of the study areas. Thereby, the stereoscopic triplet is in an enhanced acquisition mode compared to that of previous optical sensors (e.g., Quickbird, IKONOS). The tri-stereo images are composed of three nearly simultaneously acquired images, one backward (B) looking, one forward (F) looking, plus a third near-nadir (N) image [14]. This configuration, in particular the use of the near-nadir image, allows a better retrieval of heights over terrains where the performance of classic photogrammetry with forward and backward-looking stereo pairs may be limited (e.g., high roughness, steep slopes, and shadows), and allows the calculation of dense photogrammetric point clouds by using three image pairs. The Pleiades mission is programmed to continue for several years [15], and the tri-stereo acquisition mode is set to become a common feature in future satellite missions. Recently, Pleiades data have been employed for DEM generation over mountainous terrain in several studies, estimating submeter to meter scale elevation changes that are associated with natural phenomena, such as earthquakes and glaciers [16]. [PERSON] et al. [17] used SPOT5 and Pleiades DEM to calculate geodetic mass balance on Mera and Pokalde glacier (Nepal). [PERSON] et al. [16] tested the use of Pleiades imagery in glaciology on four different sites worldwide with promising results. [PERSON] et al. [18] used Pleiades DEM for glacier mass balance estimates at Muztag Ata (Pamir). [PERSON] et al. [19; 20] applied digital image matching to Pleiades data to generate accurate, high-resolution surface velocity maps, and used derived DEMs to calculate the glacier mass balances of the Monte Tronador glaciers in the Patagonian Andes. An advantage of the Pleiades satellites to applications in complex, high-relief terrain is the ability to acquire tri-stereo data in a single overpass, which minimizes the problems caused by shadowing [21; 22]. In contrast to the previous studies, we employ redesigned pixel-matching algorithms and dense matching algorithms inherited from photogrammetry to generate DEMs from the Pleiades imagery [23]. This paper presents an analysis of the quality and suitability of Pleiades tri-stereo data, which was processed using these photogrammetric techniques, for glaciological applications in mountainous terrain. First, the quality of Pleiades-derived DEM is evaluated against high accuracy airborne laser scanning data (ALS) in a well-studied region of the European Alps with relatively simple geometry and second, the same photogrammetric digital terrain model (DTM) generation workflow is applied to study glacier volume changes in a more complex terrain and the glacier geometries of the eastern Nepalese Himalaya. In addition, as has been demonstrated already by [PERSON] et al. [19], image correlation is used to determine the glacier movement based on multitemporal orthoimages derived from the Pleiades data.