NOVELTY - Preparation (M1) of duloxetine (I) or its salts, preferably duloxetine hydrochloride, involves reacting (S)-3-(methylamino)-1-thiophen-2-yl-propan-1-ol (IIa) or its N,N-dimethyl derivative (IIb) with a naphthalene derivative (IIIa) to give duloxetine (I) or N,N-dimethyl-((S)-3-(naphthalen-1-yloxy)-3-thiophen-2-yl-propyl)-amine (Ia); converting the dimethyl compound (Ia) into (I); and optionally converting (I) into its acid addition salt.    USE - For the preparation of duloxetine or its salts useful in pharmaceutical composition (claimed) useful as antidepressant and for alleviation of incontinence.    ADVANTAGE - The process provides duloxetine hydrochloride with enantiomeric purity of more than 99.7 (preferably 100)%, and chemical purity of more than 99.5 (preferably more than 99.9)%. The process is: (i) performed without intermediate conversion and isolation of (S)-N,N-dimethyl-3-(naphthalen-1-yloxy)-3-(thiophen-2-yl)propan-1-amine oxalate, which in the complete process represents two steps less in a synthesis process; (ii) it includes a direct entry of a solution of (S)-N,N-dimethyl-3-(naphthalen-1-yloxy)-3-(thiophen-2-yl)propan-1-amine into demethylation step (i.e. one pot synthesis); it uses organic acids in the precipitation step and optionally in the recrystallization of duloxetine salt step. The process is economically acceptable, environmentally friendly and technologically simple.    DETAILED DESCRIPTION - Preparation (M1) of duloxetine (I) or its salts, preferably duloxetine hydrochloride, involves reacting (S)-3-(methylamino)-1-thiophen-2-yl-propan-1-ol derivative of formula (IIa) with naphthalene derivative of formula (IIb) to give duloxetine (I) or N,N-dimethyl-((S)-3-(naphthalen-1-yloxy)-3-thiophen-2-yl-propyl)-amine (Ia); converting the dimethyl compound (Ia) into (I); and optionally converting (I) into its acid addition salt (IIIa).    R=H or CH3;    X=leaving group (preferably halo, more preferably F);    Q=anion (preferably Cl).    INDEPENDENT CLAIMS are included for the following:    (1) use of an organic acid, selected from formic acid, acetic acid, propanoic acid, and/or butanoic acid (more preferably acetic acid), in the preparation of a duloxetine salt with an acid, where the acid is selected such that it provides the anion of the target duloxetine salt, preferably hydrochloride, and optionally in the recrystallization of the formed duloxetine salt; and    (2) duloxetine hydrochloride with enantiomeric purity of more than 99.7 (preferably 100)%, and chemical purity of more than 99.5 (preferably more than 99.9)%, preferably obtainable according to the process (M1).