Reduction of the optical reflectance to an absolute minimum by the metal‐assisted chemical etching (MACE) is investigated for the p‐type crystalline silicon (100) plane wafers. The amount of the Cu additive and the composition of the etching solution identified by the proportion HF/(HF + H2O2) are the main variable parameters controlling the one step MACE. Pyramid like structures are produced on the surfaces. An influence of the variables on the surface topography and the related optical reflectance spectra is studied by measuring the spectra in the interval of the wavelengths from 400 to 1400 nm. Presence of a minimum that limits a reduction of the optical reflectance by the maskless micro‐texturing of a smooth surface of a silicon wafer is experimentally demonstrated. The crucial stage in the etching is identified by the relative depth of the etched dips that results in the lowest reflectance. Under strictly controlled conditions the minimum reflectance is obtained using etchant with 0.08 M Cu‐added. The lower and higher amounts of added Cu lead to an increase in the reflectance. The etching is explained by the localized microscopic galvanic cell model including the formation of the Cu‐nanoparticles during the MACE and the changes in the reflectance are related to an enlargement of the etched pyramids.