Guanyl thiourea (CAS 2114-02-5), also known as amidinothiourea, is a white crystalline organic powder (C2H6N4SC sub 2 H sub 6 N sub 4 SC2H6N4S) with a melting point above 159°C159 raised to the composed with power C159 °C. It is primarily used as an intermediate for pharmaceutical synthesis, in metal surface treatments (rust inhibitors), and for removing residual chlorine in wastewater. It acts as a thiourea derivative.