A process for preparing an anti-reflective sol-gel coating composition comprising: a) first mixing a hydrolysable silicon alkoxide, one or more (C 1 -C 8)alcohols, an aqueous solution of at least one acid catalyst; and one or more surfactants of formula: HO(CH 2 CH 2 O) m R 9 then maintaining the resulting mixture at a temperature comprised from 50°C to 120°C for an appropriate period of time; and finally cooling the mixture until reaching a temperature comprised from 30°C to 50°C, wherein: R 9 is (C 1 -C 30)alkyl, and m is an integer selected from 2 to 40; the concentration of the surfactant of formula in the resulting first mixture is comprised from 150 g/L to 300 g/L; the molar ratio between the hydrolysable silicon alkoxide and the aqueous solution of acid catalyst is comprised from 0.15 to 1; and the molar ratio between the hydrolysable silicon alkoxide and the (C 1 -C 8)alcohol is comprised from 0.15 to 0.30, and the molar ratio between the hydrolysable silicon alkoxide and the surfactant of formula is comprised from 7 to 11.5; b) preparing a second mixture by mixing one or more (C 1 -C 8)alcohols, and an aqueous solution of at least one acid catalyst; and maintaining the resulting mixture at a temperature comprised from 15°C to 30°C; c) adding the second mixture obtained in step b) to the resulting mixture of step a); and maintaining the resulting mixture at a temperature comprised from 30°C to 50°C for an appropriate period of time; and d) cooling the resulting mixture obtained in step c) until reaching a temperature comprised from 15°C to 30°C; and adding one or more (C 1 -C 8)alcohols until the molar ratio between the hydrolysable silicon alkoxide and the (C 1 -C 8)alcohol in the anti-reflective sol-gel coating composition is comprised from 0.025 to 0.100 wherein: the concentration of the surfactant of formula in the anti-reflective sol-gel coating composition is comprised from 55 g/L to 90 g/L, the molar ratio between the hydrolysable silicon alkoxide and the aqueous solution of at least one acid catalyst is comprised from 0.050 to 0.350, and the molar ratio between the hydrolysable silicon alkoxide and the surfactant of formula is comprised from 7 to 11.5. a) first mixing a hydrolysable silicon alkoxide, one or more (C 1 -C 8)alcohols, an aqueous solution of at least one acid catalyst; and one or more surfactants of formula: HO(CH 2 CH 2 O) m R 9 then maintaining the resulting mixture at a temperature comprised from 50°C to 120°C for an appropriate period of time; and finally cooling the mixture until reaching a temperature comprised from 30°C to 50°C, wherein: R 9 is (C 1 -C 30)alkyl, and m is an integer selected from 2 to 40; the concentration of the surfactant of formula in the resulting first mixture is comprised from 150 g/L to 300 g/L; the molar ratio between the hydrolysable silicon alkoxide and the aqueous solution of acid catalyst is comprised from 0.15 to 1; and the molar ratio between the hydrolysable silicon alkoxide and the (C 1 -C 8)alcohol is comprised from 0.15 to 0.30, and the molar ratio between the hydrolysable silicon alkoxide and the surfactant of formula is comprised from 7 to 11.5; b) preparing a second mixture by mixing one or more (C 1 -C 8)alcohols, and an aqueous solution of at least one acid catalyst; and maintaining the resulting mixture at a temperature comprised from 15°C to 30°C; c) adding the second mixture obtained in step b) to the resulting mixture of step a); and maintaining the resulting mixture at a temperature comprised from 30°C to 50°C for an appropriate period of time; and d) cooling the resulting mixture obtained in step c) until reaching a temperature comprised from 15°C to 30°C; and adding one or more (C 1 -C 8)alcohols until the molar ratio between the hydrolysable silicon alkoxide and the (C 1 -C 8)alcohol in the anti-reflective sol-gel coating composition is comprised from 0.025 to 0.100 wherein: the concentration of the surfactant of formula in the anti-reflective sol-gel coating composition is comprised from 55 g/L to 90 g/L, the molar ratio between the hydrolysable silicon alkoxide and the aqueous solution of at least one acid catalyst is comprised from 0.050 to 0.350, and the molar ratio between the hydrolysable silicon alkoxide and the surfactant of formula is comprised from 7 to 11.5.