Photocatalytic oxidation using TiO2 is one way to deal with pollutant compounds. Due to literature data, further improvement can be achieved by using MWCNT-based nanocomposites as photocatalysts. TiO2/multiwall carbon nanotube composite photocatalysts were synthetized by sol–gel method with different level coverages. As-prepared catalysts were characterized with transmission electron microscopy, scanning electron microscopy and X-ray diffraction (XRD). These investigations revealed that we could fabricate MWCNT composite either homogenously, inhomogenously or barely coated with TiO2. XRD results showed that after annealing the amorphous titanium oxide–hydroxide formed anatase phase titanium dioxide which is photocatalytically more active than rutile phase TiO2. Catalysts were tested in both gas and liquid phase photocatalytic reactions using Aeroxide (Degussa) P25 as reference. The concentrations of model compounds were measured by GC and HPLC techniques. As a result of catalytic tests, we have found correlation between morphology and photocatalytic activity. Preferred adsorption of test molecules on MWCNT surface can be a key step of the reaction.