Delayed setting times may limit the use of mineral trioxide aggregate (MTA) in endodontic procedures. The purpose of this study was to identify types and amounts of MTA additives to enhance its setting properties. Additives tested include saline, 2% lidocaine, 3.0% NaOCl gel, chlorhexidine gluconate gel, K-Y Jelly, 3% and 5% CaCl2. The setting times were evaluated using a Vicat apparatus; compressive strengths of set materials were evaluated with an Instron machine. NaOCl gel, K-Y Jelly and 5% CaCl2 decreased the setting time to 20 to 25 min; compressive strengths of these set materials were significantly lower than MTA mixed with water (p < 0.05). Because MTA mixed with NaOCl gel demonstrated good working properties and improved setting time, this combination may be a viable option in single visit procedures where compressive strength of the material is not a critical issue.