NOVELTY - Preparing substantially pure strontium ranelate (I), comprises e.g. : (a4) contacting substituted methyl 5-amino-cyano-3-(methoxy-oxoethyl)thiophene-carboxylate derivative (II) and substituted methyl acetate compounds (VII) to get substituted methyl 5-(bis(methoxy-oxoethyl)amino)-cyano-3-(methoxy-oxoethyl)thiophene-carboxylate derivative (III); (a5) optionally purifying (III) to get pure tetra alkyl ester compound (III); and (a6) contacting (III) and strontium hydroxide in water at temperature below reflux temperature of water for not more than 5 hours, precipitate obtained is filtered.    USE - The process is useful for producing strontium ranelate (I) and its hydrate (claimed) which is used for treating bone diseases. No biological data given.    ADVANTAGE - The process: provides substantially pure strontium ranelate which is substantially free of impurities; has shorter reaction time and produces (I); is environment friendly; utilizes optimized volume of water that will facilitate hydrolysis to completion (keeping solubility concept of strontium hydroxide as well as strontium ranelate in the view), at lower temperature than reflux of water for shorter duration and also the molar equivalent of strontium hydroxide used for the hydrolysis, thus eliminating or minimizing the formation of undesirable side product of (III); utilizes pure keto dicarboxylate which is substantially free from the degradation product with purity of at least 98%; and is industrially viable and economical and resulting in higher yield with total impurities less than 0.5%.    DETAILED DESCRIPTION - Preparing substantially pure strontium ranelate (I) and its anhydrate of formula (n-anhydrate), comprises: (a1) contacting substantially pure ketonic dicarboxylic acid ester of formula (RO-C(=O)-CH2-C(=O)-CH2-C(=O)-OR) (IV) with malononitrile (V) in a solvent, in presence of a base to yield substituted dimethyl 3-(1-methylethylidene)pentanedioate compounds of formula (RO-C(=O)-CH2-C(=C(CH3)(CH3))-CH=CH-C(O-)(OR) (B1H+) (VI); (a2) contacting (VI) with sulfur to yield substituted methyl 5-amino-4-cyano-3-(2-methoxy-2-oxoethyl)thiophene-2-carboxylate derivative of formula (II); (a3) optionally purifying (II) containing 7-12% moisture content using a first solvent medium comprising a solvent and an anti-solvent; (a4) contacting (II) with substituted methyl acetate compounds of formula (X-CH2-C(=O)-OR) (VII) in organic solvent in presence of base, optionally in presence of phase transfer catalyst to yield substituted methyl 5-(bis(2-methoxy-2-oxoethyl)amino)-4-cyano-3-(2-methoxy-2-oxoethyl)thiophene-2-carboxylate derivative of formula (III); (a5) optionally purifying crude compound (III) using a second solvent medium comprising a solvent and an anti-solvent to produce pure tetra alkyl ester compound of formula (III); and (a6) contacting (III) with strontium hydroxide in water at temperature below reflux temperature of water for not more than 5 hours, the precipitate obtained is filtered and dried to yield (I) and hydrates of (I).    R = linear or branched 1-6C alkyl;    B1 = base;    n = 0, 1 or 3; and    X = halo.    An INDEPENDENT CLAIM is also included for preparing substantially pure strontium ranelate (I) and its hydrates (IA) comprising step (a6) as above per se.