The GOES-16 satellite was launched on 19 Nov 2016, and it became operational as the GOES-East satellite on 18 Dec 2017. The Advanced Baseline Imager (ABI) is one of six instruments onboard GOES-16. It has 16 spectral bands, a spatial resolution of 0.5-2.0 km, and five times the temporal coverage of the previous GOES Imager. ABI has onboard radiometric calibration capabilities that were not available on the previous Imager instrument. The Radiometric Calibration Test Site (RadCaTS) is an automated facility composed of ground-based instruments that measure the surface reflectance and atmosphere throughout the day. It was developed by the Remote Sensing Group (RSG) of the College of Optical Sciences at the University of Arizona, and it is currently used to monitor such low-Earth orbit (LEO) sensors as Landsat-8 OLI, Terra and Aqua MODIS, Sentinel-2A and-2B MSI, SNPP VIIRS, and others. The successful launch of GOES-16, coupled with the improved spectral, spatial, and temporal characteristics of ABI, provide a unique opportunity to intercompare results obtained from a geosynchronous sensor to those obtained from typical LEO sensors. This work describes the recent efforts of RSG to validate the radiometric calibration of ABI, and compare the results with LEO sensors using RadCaTS.