Reflection loss of silicon solar cells can be reduced by texturization of the surfaces. In this study, single- and multi-crystalline silicon substrates were treated with chlorine trifluoride (ClF3) to create honeycomb-textured structures. We investigated surface structures and optical properties of the textured surfaces. By the treatment with ClF3 gas, the reflectance of the textured surface without anti-reflection coating was obtained to be below 20% at wavelengths between 300 and 800nm. The solar cells using the textured substrates were fabricated and their improved performances were demonstrated. circle dot 2007 Elsevier B.V. All rights reserved.