NOVELTY - Improved process for the preparation of carbapenem compounds (I), comprises condensing a (5R,6S)-6-((R)-1-Hydroxy-ethyl)-7-oxo-1-aza-bicyclo(3.2.0)hept-2-ene-2-carboxylic acid compound (A) with protected side chain compound (B) using an inorganic base such as alkaline earth meal oxide/transition metal oxide in an organic solvent to produce protected carbapenem compound (III), and hydrogenating (III) using hydrogen and a metal catalyst in an organic solvent to produce (I).    USE - The improved process is useful for the preparation of (I), preferably meropenem trihydrate (all claimed). (I) are useful for treating bacterial infections and include ertapenem, doripenem, faropenem, panipenem and biapenem. No biological data given.    ADVANTAGE - The improved process ensures easy and economical preparation of (I) with high yield and purity in an eco-friendly manner. The metal oxide used in the process is easy to handle to on large scale as it is non-corrosive, environmental friendly and personnel friendly (no-smell and non-toxic).    DETAILED DESCRIPTION - Improved process for the preparation of carbapenem compounds of formula (I) and/or their stereoisomers, hydrates or salts, comprises condensing a (5R,6S)-6-((R)-1-Hydroxy-ethyl)-7-oxo-1-aza-bicyclo(3.2.0)hept-2-ene-2-carboxylic acid compound of formula (A) with protected side chain compound of formula (-HS-Gr1) (B) using an inorganic base such as alkaline earth meal oxide/transition metal oxide in an organic solvent to produce protected carbapenem compound of formula (C), and hydrogenating (C) using hydrogen and a metal catalyst in an organic solvent to produce (I).    R = H or 1-3C alkyl;    Gr = (5S)-1-carboxy-5-(dimethylcarbamoyl)pyrrolidin-3-yl, (5S)-5-((3-carboxyphenyl)carbamoyl)pyrrolidin-3-yl, (5S)-5-((sulfamoylamino)methyl)pyrrolidin-3-yl, 2-methanimidamidoethyl or 6,7-dihydro-5H-pyrazolo(1,2-a)(1,2,4)triazol-4-ium-6-yl;    Gr1 = monovalent groups of formulae (a)-(d) or 6,7-dihydro-5H-pyrazolo(1,2-a)(1,2,4)triazol-4-ium-6-yl;    P1 = H or a carboxy protecting group; and    P2, P3 = nitrogen protecting groups.    An INDEPENDENT CLAIM is included for the preparation of meropenem trihydrate (Ia), comprising condensing a (4S,5R,6S)-6-((1R)-1-hydroxyethyl)-4-methyl-7-oxo-1-azabicyclo(3.2.0)hept-2-ene-2-carboxylic acid compound of formula (A1) with ((5S)-5-(dimethylcarbamoyl)-1-((4-oxidoazonoylphenyl)methoxycarbonyl)pyrrolidin-3-yl)sulfanyl (B1) using magnesium oxide in the organic solvent to produce protected meropenem of formula (C1) and hydrogenating (C1) using hydrogen gas and the metal catalyst in the organic solvent to produce (Ia).