Compounds of the formula ##SPC1## Wherein Ar denotes an optionally substituted phenyl group or hetero-aromatic group with 5 or 6 ring members wherein the atom directly bonded to the quinoline ring is a carbon atom, R.sub.1 represents hydrogen, halogen, lower alkyl, lower alkoxy or trifluoromethyl and R.sub.2 and R.sub.3 independently of one another denote hydrogen or a lower alkyl group, esters and amides of these carboxylic acids or salts of such compounds, have anti-inflammatory and analgesic activity; they are active ingredients of pharmaceutical compositions and can be used for the relief and removal of pain as well as for the treatment of rheumatic, arthritic and other inflammatory complaints; an illustrative example is .alpha.-methyl-2-(2-thienyl)-6-quinolineacetic acid.