Lepidocrocite potassium magnesium titanate having a composition represented by the formula K.sub.0.2-0.7Mg.sub.0.4Ti.sub.1.6O.sub.3.7-4 and obtainable by subjecting an aqueous slurry of lepidocrocite potassium magnesium titanate having a composition represented by the formula K.sub.0.8Mg.sub.0.4Ti.sub.1.6O.sub.4 to an acid treatment and subsequent calcination.