This work focuses on the preparation of novel ternary transparent conducting oxide coatings on glass by the sot-gel method. The coatings were deposited by spin-coating from solutions of appropriate metal precursors and heat-treated at different heat-treatment procedures. An increase in electrical conductivity was achieved by a final forming gas treatment. Best electrical and optical properties have been obtained for coatings of crystalline Zn
2
SnO
4
, Zn
3
In
2
O
6
and Zn
5
In
2
O
8
and X-ray amorphous ZnSnO
3
with resistivities in the order of 10
-2
-10
-1
Ωcm, an average transmission in the visible of 85% and an average surface roughness of similar to 1 nm. ZnGa
2
O
4
and GaSbO
4
coatings showed no electrical conductivity. For Zn
2
SnO
4
coatings, a restricted crystallite growth was observed probably due to phase segregation effects. Electrical properties of coatings in the system ZnO-In
2
O
3
were interpreted on the basis of the percolation theory.