A process for preparing particles of a layered double
hydroxide of the general formula [Mp z+ M'q y+ (OH)2]a+(Xn-)a / n.bH2O (I) wherein Mz+ and M'y+ are
metal cations or mixtures of
metal cations, z =1 or 2; y = 3 or 4; p + q = 1; b = 0 to 10, Xn- is an anion, n is 1 to 5 and a is determined by p, q, y and z such that a = zp+yq-2 comprises (a) mixing, in
aqueous solution, Mz+ cations, M'y+ cationsand Xn- anions, with a base; and (b) allowing the layered double
hydroxide of formula (I) to precipitate from the solution mixed in step (a). Preferably, M is Li, Mg, Zn, Fe, Ni, Co, Cu, Ca, or a mixture of two or more. Preferably, y is 3 and M' is Al, Ga, In, Fe or a mixture of two or more thereof. Also provided are particles obtainable by the process, especially wherein M is Ca, M' is Al and Xn- is NO3-. Particles of a layered double
hydroxide wherein the particles have a particle size of not greater than 2000 nm, preferably not greater than 300 nm and especially not greater than 100 nm, are also provided. The
layered double hydroxides according to the invention are useful in certain applications, for example, as adsorbents, coatings and catalyst supports.