Hydrogels with reactive thiourea functional groups were prepared by radiation-induced crosslinking of N-(Hydroxymethyl) acrylamide (HMA) and N-allyl thiourea (ATU) at different ATU content and irradiation doses. P (HMA-co-ATU) hydrogels were then utilized as template for in situ metal nanoparticle (MNP) preparation by the reduction of Ni2+, Co2+, and Cu(2+)ions within the hydrogel matrix using sodium borohydride (NaBH4) as reducing agent. These MNP@p(HMA-co-ATU) hydrogel composites (MNP = Co, Ni, and Cu) were further used as catalysts in the reduction reaction of 4-nitrophenol (4-NP) to 4-aminophenol (AP). Various parameters such as the effect of ATU content, the total dose used in the hydrogel preparation, MNPs type, and temperature on the catalytic activity of hydrogel composites were investigated. The activation energy, enthalpy, and entropy of Ni@p(HMA-co-ATU) hydrogels for the reduction reaction of 4-NP to 4-AP were calculated as 42.5 kJ mol-1, 38.9 kJ mol(-1), and-187.3 J mol(-1) K-1, respectively.