Transparent TiO
2
films were produced via sol-gel spin and dip-coating techniques. Soda-lime glass (SLG) and SiO
2
precoated glass were used as substrates. The thin films were characterized by X-ray diffraction (XRD), X-ray reflectometry (XRR), optical profilometer and glow discharge optical emission spectroscopy (GD-OES). Na migration was detected in the amorphous TiO
2
films which are deposited on SLG substrates. In order to prevent sodium migration a barrier layer was introduced between TiO
2
film and glass. The beneficial role of this barrier layer on alkali migration is verified and the mechanism of prevention of migration is proposed relying on the results of GD-OES depth profile measurements.