A high pressure, high temperature, seatless cut-off valve particularly suitable for use with solid materials. The construction employs a sleeve valve reciprocable past aligned ports between concentric tubular housing members under conditions wherein the pressure conditions acting on the valve are fully neutralized at all times. Pressure neutralizing is achieved by passageway means interconnecting chambers embracing the end portions of the sleeve valve and encircling the valve in the area of its flow port and between sets of sealing rings to either axial side of this port. All surfaces contacted by the flowing fluid are preferably lined with protective laminate such as thick ceramic having a protective skin of tough abrasion resistant alloy.