Angular distributions of the decay B0→K⁎0μ+μ− are studied using a sample of proton–proton collisions at s=8TeV collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 20.5fb−1. An angular analysis is performed to determine the P1 and P5′ parameters, where the P5′ parameter is of particular interest because of recent measurements that indicate a potential discrepancy with the standard model predictions. Based on a sample of 1397 signal events, the P1 and P5′ parameters are determined as a function of the dimuon invariant mass squared. The measurements are in agreement with predictions based on the standard model.