The role of several additives in electrolytic solution during silicon anodization was reported in this paper. The morphologies of macroporous silicon arrays in low-doped n- or p-type silicon are strongly influenced by the chemical nature of these additives. Conventional solvents (ethanol and acetic acid), non-ionic (Triton-X100 and Brij35) and ionic (cetyltrimethylammonium chloride and ammonium dodecylsulfate) surfactants were experimented. Prominent differences in macropore morphologies and porosities were observed depending on the chemical nature of the additive. The different behaviors of the additives during the electrochemical etching process were linked to the physical properties of the additives. We found that the wetting ability of the molecules partially explains these results. However, charged molecules adsorption is also assumed to influence the silicon etching isotropy either by decreasing or increasing the porosity of the macropores depending on their anionic or cationic property. (C) 2013 The Electrochemical Society. [DOI: 10.1149/2.013306jes] All rights reserved.