Hi, I think the subject of the message is explicit enough... Perhaps the option of having a default color different than cyan for hydrogen bonds already exists, but I have failed to find it. I have this line in my .chimera/preferences file: 'FindHBonds': {'line width': 2.0}, So I tried to include something like 'color: (0.0, 0.0, 0.0, 1.0)' (or bond color or H-bond color...) in the FindHBonds dictionary, alas without success. Let me give some rationale: I prefer having a white background, against which cyan is not really very visible when the structure gets complex. Not to me eyes at least. Thank you! Best regards, -- Miguel Architecture et Fonction des Macromolécules Biologiques (UMR7257) CNRS, Aix-Marseille Université Case 932, 163 Avenue de Luminy, 13288 Marseille cedex 9, France Tel: +33(0) 491 82 55 93 Fax: +33(0) 491 26 67 20 mailto:miguel.ortiz-lombardia@afmb.univ-mrs.fr http://w2.afmb.univ-mrs.fr/Miguel-Ortiz-Lombardia