A theoretical analysis, based on the linearized equation for supersonic flow, of characteristics of triangular-tip control surfaces on thin triangular wings. By restriction to case for which Mach lines from wing apex lie behind the leading edge, a simplified treatment was possible; results of previous work on lift of triangular wings could be used to derive expressions for lift effectiveness, pitching moment, rolling-moment effectiveness, hinge moment due to control deflection, and hinge moment due to angle of attack. Comparisons were made with two-dimensional case.