The paper introduces a straightforward method to measure intrinsic channel maldistribution in monolithic structures in gas-solid operation. The experimental procedure is non-destructive for the monolith and easy to perform but special care has to be taken to prevent leakage. The method is demonstrated for squared channel monoliths of 100 and 400 cells per square inch (cpsi). Variances in the production process of monoliths introduce an intrinsic channel maldistribution that can be described by a normal distribution. As a consequence, the assumption that a monolith is a bundle of equal channels is incorrect and may introduce significant errors in mathematical models that do not incorporate intrinsic channel maldistribution.