We show that the proton impurity in a neutron matter can create an inhomogeneity in density which acts as a potential well localizing the proton’s wave function. At low densities this inhomogeneity is a neutron bulge, whereas at high densities a neutron deficiency (bubble) occurs. We calculate variationally the proton’s energy using a Gaussian wave function. The neutron background is treated in a Thomas–Fermi approximation. The Skyrme interactions are used. We find that the localized proton has lower energy than the plane wave proton for densities below the lower critical density n1≅ 0.3n0, and above the upper critical density nu≅ 2.2n0, where n0 = 0.17 fm−3. We discuss some implications of the proton localization for magnetic properties of neutron matter containing a small admixture of protons