The contribution deals with possibilities of chemical formulas presentation on web site. It briefly characterizes the image, MathML and CML as well as web service application for this purpose. Paper specifies web service arrangement, its principle, functions and requirements. The concrete example illustrates its exploitation. Described web service is assigned to chemical formula conversion from standard ASCII form to HTML form that displays the atoms count or ions valence in form of subscripts or superscripts. Web service can be a part of other service or building component of other web application.