This research aims at the utilization of both calcareous and siliceous lignite ashes, by-products of lignite combustion in power plants, toward a development of new materials of an environmental benefit. The possibility of fly and bottom ash surface modification by anatase and rutile (titanium dioxide structures) is investigated. The precipitation of TiO2 from an acidic solution on lignite ash surface is studied and the percentage of TiO2 coating obtained is found ranging from 11 to 55%. The latter microstructure is examined by XRD and SEM-EDX taking into consideration the ashes particle size (as received and < 45 µm), the solution pH (5.5 - 7.5), the ageing time (1 and 3 h) and the sintering temperature (300°C, 500°C, 700°C) applied. Anatase and rutile crystalline structures are observed within the whole heat treatment range. The main advantage of the process reported refers to titania immobilization onto a cheap porous substrate providing an additional solution to liquid wastes treatment by photocatalysis. [ABSTRACT FROM AUTHOR]