NOVELTY - Use of a catalyst (I) comprising a mixed oxide in a basic heterogeneous catalyzed chemical reaction is claimed, where (I) is obtained by calcining a bilayer metal hydroxide (II).    USE - (I) is useful in a basic heterogeneous catalyzed chemical reaction, which is a transesterification, preferably triglyceride transesterification for preparing biodiesel and aldol condensation (both preferred), transetherification, saponification or cleavage of beta -dicarbonyl compound. (I) is useful as adsorbent. (I) is useful for the preparation of carboxylic acid ester from triglycerides and alcohols or of alpha , beta -unsaturated carbonyl compounds (all claimed).    ADVANTAGE - (I) carries out the catalyzed heterogeneous chemical reaction in a moderate reaction conditions and provides high product yield.    DETAILED DESCRIPTION - Use of a catalyst (I) comprising a mixed oxide in a basic heterogeneous catalyzed chemical reaction is claimed, where (I) is obtained by calcining a bilayer metal hydroxide of formula (((M1+)y(M2+)1-y-x(M3+)x(OH)2)(x-y)+(A)(x-y)/n(n-).mH2O) (II).    M2+ = at least a divalent inorganic cation comprising Mg2+, Ca2+, Sr2+, Ba2+, Zn2+, Cd2+, Cu2+, Ni2+, CO2+, Fe2+, Pb2+ or Sn2+;    M1+ = at least one monovalent inorganic cation comprising alkali metals+, Cu+ or Ag+;    M3+ = at least one trivalent rare earth metal cation or a mixture of at least one trivalent rare earth metal cation and at least one another trivalent inorganic cation comprising Al3+, B3+, Ga3+, Cr3+, Mo3+, In3+ or Fe3+;    A = an inorganic or organic anion; either    x = 0.05-0.95; and    y = 0-0.95; or    x+y = less than or equal to 1;    n = 1-4; and    m = 0.1-2.    INDEPENDENT CLAIMS are included for:    (1) the preparation of (II) comprising coprecipitation of M3+-metal salts, M2+-metal salts and/or M1+ metal salts from a aqueous solution using a precipitating agent, which is potassium carbonate or a mixture of potassium carbonate and potassium hydroxide;    (2) the bilayer metal hydroxide (II) with a Brunauer-Emmett-Teller surface of 110-300 m2/g; and    (3) the mixed oxide catalyst (I).