The magnetization and anisotropic properties of single crystal Co and Cu‐18H‐layer hexagonal ferrites are reported. Magnetization measurements of these microwave materials were made from 4.2°K to Tcin fields up to 15 kOe. While theCo‐18Hhas an easy plane and Cu‐18H has an easy axis (c) of magnetization,Ea = K1sin2&thgr; + K2sin4&thgr;is applicable to both. The magnetization of Co‐18H was saturated at all temperatures and exhibited a Ne´el M type Msvs T curve. In hysteresis loops of Cu‐18H above 58°K constrictions were present. In sharp contrast to barium ferrite, Hcvs T decreases exponentially. The Tcvalues are495±6°Kand530±8°K, respectively for Co and Cu‐18H. A moment for Co‐18H,n&bgr;(H=∞, T=0) = 9.6&mgr;&bgr;was found.