Single crystals of barium substituted calcium tartrate tetrahydrate (CBT) with molecular formula Ca0.8Ba0.2C4H4O6.4H(2)O have been grown in gels using a chemical reaction method at ambient temperature. Linear optical properties of this material such as refractive indices, birefringence and absorption characteristics were measured in the wavelength range 200-1400 nm. No dispersion of the birefringence was observed within the experimental accuracy. The second harmonic generation efficiency of CBT is two times that of quartz. Dielectric measurements were determined in the frequency range 100 Hz-1000 MHz. CBT exhibits polar characteristics. The electrical resistance of CBT was measured from room temperature up to 200degreesC. According to the accurate measurements of the above-mentioned parameters, it seems likely that CBT undergoes structural change. The TG/DTA thermogram is used to confirm the observed structural change. CBT is found to be diamagnetic. (C) 2002 Elsevier Science B.V. All rights reserved.