PDMS (Polydimethylsiloxane) is a typical material used to fabricate optofluidic microreactors for photocatalytic water splitting application. However, conventional direct catalyst coating methods are unable to load catalysts firmly and uniformly on the PDMS substrate, which results in weak bond between the catalysts and substrate and thus poor durability and performance. To resolve this problem, a new casting-transfer method was proposed for loading catalysts on the PDMS substrate to fabricate the optofluidic microreactor in this work. By performing the tape testing and long-term testing, it was shown that the optofluidic microreactor fabricated by the new method exhibited critically high durability as compared to the conventional one. The hydrogen production rate was also higher than the conventionally fabricated microreactor. In addition, it was found that the optofluidic microreactor with the micro-grooved structure yielded higher hydrogen production rate than did the conventional planar optofluidic microreactor as a result of enhanced mass transport and reaction area. This method creates a new avenue to fabricate the PDMS based microreactors with high durability. (C) 2015 Elsevier Ltd. All rights reserved.