Water content reflectrometers (WCR) have been used for field experiments to acquire water content data to estimate the soil water balance, plant water use, and irrigation scheduling. Calibration of WCR is required for soils containing smectitic clays. The objective of this research was to develop calibration relationships for WCR in claypan soils and examine responses affected by temperature. The study design consisted of three replicates of surface and subsurface horizon soil materials from a Putnam silt loam. Temperatures ranged from 5 to 40 degrees C with 5 degree increments. Soil was packed to a uniform density in columns, 10 cm diam. by 54 cm long. Sensors were inserted into the soil columns and connected to a datalogger to record period and volumetric water content. WCR measured period and volumetric soil water content were highly correlated but dependent on clay content and temperature. Measured period increased with increasing temperature for all soil materials. The effects of temperature varied with soil water and clay content. Calibration relationships were developed for different soil horizons with varying clay content. Coefficients of determination for the surface and subsurface soils ranged from 0.96 to 0.99 for the linear and quadratic calibration equations. Results indicate that WCR sensors must be calibrated when using smectitic clays in order to provide accurate readings.