Barium thiourea chloride (BTC) single crystals were grown by slow evaporation of aqueous solution containing barium chloride and thiourea in the equimolar ratio. Thermal analysis of the grown crystal was carried out by thermogravimetric analysis (TGA)/DTG and the thermal parameters such as enthalpy, entropy and the activation energy were calculated. The AC conductivity and impedance measurements were carried out using conventional two probe technique in the temperature range of 300–400 K and in the frequency range of 100 Hz to 5 MHz. The conductivity was found to be very low and slowly increasing with the frequency with a peak around 5 MHz. Real and imaginary parts of complex impedance were determined for the grown sample as a function of frequency. Good transparency and thermal stability suggest BTC single crystals can be used for optical applications. © 2016 Informa UK Limited, trading as Taylor & Francis Group.