Ceramics and glasses are frequently applied in the manufacture of electronic products. The production of ceramic components is based on the compaction of a powder, followed by a high-temperature (sintering) step giving the final product. The compaction method can be the dry pressing of the powder or a process in which the powder is in suspension, e.g. slip-casting or colloidal pressing. Features of the powders which are governed by the surface properties such as agglomeration, suspension stability, powder flow and compactability influence this compaction strongly. In this letter a method is described to change the surface properties of powder particles by a chemical reaction of organic acids with the surface of the powder. The method is based on the formation of a covalent bond between the surface hydroxyl groups that are often present on metal or metal oxide surfaces, and organic long-chain molecules such as carboxylic acids. After the reaction the powder surface is covered with a (sub)monomolecular layer of aliphatic chains. The modified powder may be used both in wet and in dry processes. Two different c~-aluminas (referred to as (1) cohesive, broad particle size distribution and (2) flowing, narrow particle size distribution), manganese oxide, c~-ferric oxide, two types of ferrites, glass and tungsten metal powder were each suspended in a solution of 3 wt % carboxylic acids in 1,3,5-trimethyl benzene under ultrasonic irradiation (20kHz, 50W) in an inert atmosphere at 100 ° C. This ultrasonic treatment was intended to disagglomerate the powder. The surface hydroxyl groups, present on the surface of the powder, react with the carboxylic acid (carboxylic acids have the advantage that they can be removed by burning-out later in an oxidizing atmosphere without leaving residues). After 1 h the reaction was stopped, the powders were washed several times with hot toluene or refluxed in a Soxhlet apparatus to remove the unreacted physisorbed acids and dried in vacuo at room temperature. The powders were analytical grade, the reagents were supplied by Janssen Chimica. The specific surface area (SBET) was determined before the modification from nitrogen adsorption data using the BET equation. Diffusion reflection Fourier transform infrared (DRFTIR) spectra indicated whether a bond was formed or whether the unreacted carboxylic acid was still present (Table I). Carbon analysis gave information on the amount of coating formed on the powder. The powders were tested in double-sided uniaxial and isostatic dry pressing and in suspension experiments. A specimen for uniaxial pressing experiments is prepared by filling the powder into a poly(methyl methacrylate) mould and pressing to the