Abstract Joining of Hastelloy X to Inconel 718 by a rapid infrared processing technique has been investigated at 1150 °C using a nickel-based brazing alloy AMS 4777, Ni7Cr3Fe3.2B4.5Si0.06C in wt.%. With this infrared technique, joining typically was completed in seconds in ambient argon. The effects of the infrared joining time on the joint and base material microstructures, elemental distribution within the microstructures and the resulting joint shear strength were investigated. Results show that excellent joint shear strengths of as high as 503 MPa were obtained when processed at approximately 1150 °C for 120 s. Micro-structural examinations of the joint with an optical microscope and a scanning electron microscope indicate that good wetting existed between the brazing alloy and both Hastelloy X and Inconel 718. The braze-affected zone width increased with increasing joining time but did not show a direct correlation with the joint strength. Hastelloy X and Inconel 718 exhibited no noticeable change in microstructures due to the rapid heating cycle of infrared processing.