The strength development of young masonry mortar and prism is studied through measuring the electrical properties of hydrating mortar by using TWIN-tape capacitance sensor. The dielectric properties over the frequency range of 10 kHz to10 MHz varies during hydration of mortar, providing a means for monitoring the strength development. This investigation confirms that the lower frequencies (less than 100 kHz) are very efficient in monitoring hydration of mortar. In addition, wireless sensing electronics is employed to monitor the strength gain process of young masonry prisms. Moreover, the freezing and thawing temperatures of masonry mortar and prism are identified by using three different techniques. Furthermore, the strength gain process of mortar is investigated at cold ambient temperatures, i.e. ambient temperature below 5ºC, by using dielectric measurements. This investigation reveals that the mortar gains strength at temperatures as low as 0ºC, whereas it partially freezes at -1º c and completely freezes at -2ºC.