Abstract: A slide valve for high temperature, high pressure use provides for easy access to internal components for replacement or repair, and also provides for easy and secure adjustment of the valve components from the exterior of the valve even while the valve is in position in its process line. The slide valve includes a body having a throat providing for fluid passage through the body, a shoulder within the body including passage means communicating with the throat, a side portion extending transversely from the body and having an interior space communicating with the throat, a valve seat removably positionable upon the shoulder, a guide member removably positionable within the body adjacent the shoulder and extending into the side portion, a closure member positionable slidably upon the guide member for opening and closing the passage means, and a wedge member positionable adjustably between the shoulder and the guide member. The wedge member is adjustable exteriorly of the body.