The microstructure of B2O3 and TiCl3 added Sh(2)O(3) donor-doped Ti-excess BaTiO3 compositions were investigated. Platelet type Ba2Ti5O12 was detected as a secondary phase in the Ti excess undoped composition sintered at 125 degreesC for 10 hours. This phase decreased considerably in the S6(2)O(3) and B2O5 added samples. The Sh(2)O(3) donor-doping was very effective for promoting the twin formation due to the increased concentration of the Ti-3 ions. The 0.5 mol% B2O3 addition to this composition gave rise to the polygonal type grains containing twin lamellae and Ti-rich rod-like grains. At 1 mol% the B2O3 addition level, the polygonal grains and twin lamellae grew to the order of 100 mum size in a fine grained matrix. A sudden grain growth occurred at 2 mol% the B2O3 addition level, with the loss of twin lamellae in the structure. The addition of 0.2 mol% excess TiO2 as a liquid TiCl3 form to the 0.5 mol% B2O3 containing sample, reduced the size and the number of polygonal grains and had a marked effect on the hvin formation due to the homogeneous distribution of the excess Ti ions in the composition.