The invention relates to an agrochemical composition comprising propylene carbonate, up to 10 wt % of water, and compounds I their salts, tautomers, or enantiomers; wherein the variables are as defined in the description. The invention also relates to a process for the preparation of the composition, comprising mixing the propylene carbonate, compounds I, and optionally an acid and/or cyclohexanone. It also relates to a method for controlling pests, which method comprises the application of the composition, or a dilution thereof, to plants, plant propagation material, or the locus of growth of the plants; the pests or their food supply, habitat or breeding grounds. Other objects are the use of cyclohexanone and/or an acid, in particular acetic acid, for stabilizing compositions comprising compounds I; composition for stabilizing water-soluble pesticides as defined in any of claims 1 to 9, comprising 1 to 50 wt % of propylene carbonate, 0.1 to 30 wt % cyclohexanone, and an acid; and an aqueous tank-mix composition comprising the composition in a concentration of 0.01 wt % to 10 wt % with regard to the total weight of the tank-mix.