The design of new anion exchange ionomers for use in electrochemical devices is a critical step in improvement of anionic fuel cells and electrolyzers. Although these materials share some targeted goals with anion exchange membranes (AEMs), there are several different property requirements. Since ionomers are used within electrode layers, they do not serve as a primary separator for fuel and air. Rather, they act as a transport facilitator in the electrode where a high degree of mass transport is required. In this study, a series of anionic ionomers is synthesized and tested in hybrid fuel cells and AEM electrolyzers. These ionomers are based on a series of materials which include block copolymer AEMs with alkyl tethers that have been modified to be used as anion conductors. The newly synthesized ionomers were tested in both fuel cell and electrolysis devices. In situ testing of these materials shows that lower molecular weight materials outperform their higher molecular weight counterparts. Additionally, the use of a block copolymer with the introduction of a hydrophobic spacer further increased device performance. (c) The Author(s) 2017. Published by ECS. All rights reserved.