On-site hydrogen production via catalytic ammonia decomposition presents an attractive pathway to realize H-2 economy and to mitigate the risk associated with storing large amounts of H-2. This work reports the synthesis and characterization of a dual-layer hollow fiber catalytic membrane reactor for simultaneous NH3 decomposition and H-2 permeation application. Such hollow fiber was synthesized via single-step co-extrusion and co-sintering method and constitutes of 26 mu m-thick mixed protonic-electronic conducting Nd5.5Mo0.5W0.5O11.25-delta (NMW) dense H-2 separation layer and Nd5.5Mo0.5W0.5O11.25-delta Ni (NMW-Ni) porous catalytic support. This dual-layer NMW/NMW-Ni hollow fiber exhibited H2 permeation flux of 0.26 mL cm(-2) min(-1) at 900 degrees C when 50 mL min(-1) of 50 vol% H-2 in He was used as feed gas and 50 mL min(-1) N-2 was used as sweep gas. Membrane reactor based on dual-layer NMW/NMW-Ni hollow fiber achieved NH3 conversion of 99% at 750 degrees C, which was 24% higher relative to the packed-bed reactor with the same reactor volume. Such higher conversion was enabled by concurrent H-2 extraction out of the membrane reactor during the reaction. This membrane reactor also maintained stable NH3 conversion and H-2 permeation flux as well as structure integrity over 75 h of reaction at 750 degrees C. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.