The aim of this study was to investigate the influence of doping and hydrogenation on the structural, optical and magnetic properties of dia-magnet Lanthanum oxychloride (LaOCl). LaOCl codoped with palladium and cobalt samples were successfully synthesized by solvothermal route, followed by a subsequent heat treatment process (annealing) at 600, 750 and 900 degrees C. Furthermore, annealing in hydrogen gas (hydrogenation) was carried out to the samples at 400 degrees C. The crystallite size (CS) of the samples were found to be influenced by annealing and hydrogenation processes as it ranged from 10.6 to 38 nm, as confirmed by X-ray diffraction (XRD) technique. Results also revealed dramatic changes in magnetic properties of the synthesized samples treated with annealing and hydrogenation. Vibrating sample magnetometer (VSM) analysis showed that Pd/Co-codoped LaOCl nanopowders own room temperature ferromagnetic (RT-FM) properties when post-annealed in air at 750 degrees C. It is also confirmed that created saturation magnetization is strongly affected by hydrogenation as it raised by similar to 50 time. (8.6 memu/g before and 410 memu/g after hydrogenation). The physical explanations and discussions were given in the framework of bound magnetic polarons (BMP) theory explaining how magnetic properties can be tailored from diamagnetic (DM) in pure LaOCl compound to FM under doping and hydrogenation. (C) 2017 Elsevier B.V. All rights reserved.