The present invention provides solid oral pharmaceutical compositions comprising wet milled Diclofenac acid and one or more pharmaceutically acceptable excipients and process for preparation thereof. The present invention particularly relates to solid oral pharmaceutical compositions comprising wet milled diclofenac acid with median particle size of less than 1000 nm. In addition the compositions of present invention have the comparable dissolution profiles with marketed composition of diclofenac acid. Maximum Plasma Concentration (Cmax) and Area Under Curve (AUC) values of compositions of present invention are within the limit of 80 % to 125 % of Cmax and AUC of the marketed composition of diclofenac acid capsules respectively.
