The invention provides acidic, thickened cleaning and disinfecting compositions which exhibit good long term shelf stability, are particularly effective in the removal of limescale from hard surfaces, and which are effective against gram positive and gram negative bacteria. The compositions comprise one or more non-ionic surfactants; one or more quaternary ammonium surfactant compounds having germicidal properties; an acid mixture comprising formic acid and one or more water-soluble organic acids (particularly water-soluble organic acids selected from lactic acid, citric acid, glycolic acid), preferably where the formic acid and one or more water-soluble organic acids are present in a weight ratio of formic acid: water-soluble organic acid of 1:0.1 to 1:10; a cellulose based thickening composition; optionally but desirably one or more conventional additives such as a colouring agent, fragrance or pH adjusting agent; and water. The compositions feature surprisingly good viscosity retention over time, notwithstanding the presence of formic acid and cellulose based thickeners in the compositions.