A dental bleaching composition comprises a dental bleaching agent, polyvinylpyrrolidone, and at least 0.1% water. The bleaching composition may include a liquid component, flavoring agent, basic substance, and/or desensitizing agent as desired. Polyvinylpyrrolidone avoids acid etching and chelation of teeth that were problematic in bleaches using carbomer as a thickener. A delivery system for delivering the bleaching composition comprises the aforementioned dental bleaching composition in combination with a moisture-resistant barrier layer such as a dental tray or a flexible strip of material.