A series of new 3-(4-methylcoumarinyl-7-oxymethyl)-6-substitutedphenyl-5,6-dihydro-s-triazolo (3,4-b)(1,3,4)-thiadiazoles 2(a-j) have been synthesized by reacting 5-(4-methyl coumarinyl-7-oxymethyl)-4-amino-3-mercapto(4H)-1,2,4-triazole with various aromatic aldehydes by microwave assisted organic synthesis. The structure of the compounds 2 (a-j) has been confirmed by IR, 1H NMR and mass spectral data. All the compounds were screened for antimicrobial and antioxidant activity. Among the compounds tested, compounds 2d (4-dimethyl amino phenyl derivative) and 2h (3,4-dimethoxy phenyl derivative) showed better antimicrobial and antioxidant activity than rest of the compounds in the series.