Knowledge of surface moisture on beaches is vital for aeolian process studies because moisture increases transport thresholds and limits mass flux. A number of beach surface moisture measurement techniques have been employed in the field, including sample extraction, commercial soil moisture sensors, and remote sensing techniques. Each method has significant limitations in the context of aeolian process studies. This study was designed to test infrared optic techniques for measuring beach surface moisture. A simple infrared sensor (narrow-band radiometer) was developed to measure beach surface moisture content. The accuracy and practical usability of the narrow-band radiometer were assessed in comparison to a commercial handheld spectroradiometer. Field calibrations conducted at Cape San Blas, Florida and Padre Island, Texas indicated that the narrow-band radiometer performed quite well. The R2 values exceeded 0·98 in each case, and the standard error averaged about 1% moisture content compared with gravimetric moisture contents determined from 1·5 mm deep surface scrapes. The performance of the two instruments was found to be comparable, with the narrow-band radiometer slightly outperforming the spectroradiometer. In practical applications, the narrow-band radiometer also has logistical advantages and is better suited to measure large numbers of points. Copyright © 2012 John Wiley & Sons, Ltd.