The present study reports on kinetics of borided AISI M2 high speed steel. Boronizing thermochemical treatment was carried out in a solid medium consisting of EKabor powders at 850 °C, 900 °C and 950 °C for 2, 4, 6 and 8 h, respectively. The presence of borides FeB and Fe 2 B of steel substrate was confirmed by optical microscopy and scanning electron microscopy (SEM). The results of this study indicated that the morphology of the boride layer has a smooth and compact morphology, and its hardness was found to be in the range of 1600–1900 HV. Depending on process time and temperature the thickness of boride layer measured by a digital instrument attached to an optical microscope ranged from 3 to 141 μm. Layer-growth kinetics were analyzed by measuring the extent of penetration of the FeB and Fe 2 B sublayers as a function of boronizing time and temperature. The fracture toughness of borides ranged from 4.80 to 5.21 MPa m 1/2 . Moreover, an attempt was made to investigate the possibility of predicting the iso-thickness of boride layer variation and to establish an empirical relationship between process parameters and boride layer thickness.