The synthesis and biological evaluation of some novel thieno (2,3-d)pyrimidin-4(3H)one derivatives was aimed at creating a new scaffold. Considering the previous articles activity profile of thienopyrimidinone derivatives, ten new substituted thieno(2,3-d)pyrimidin-4(3H)one derivatives have been synthesized by reacting different 2-amino-4,5-substituted thiophene-3-carbonitrile with appropriate aliphatic carboxylic acid in presence of phosphoryl trihloride and alumina by conventional synthesis as well as microwave assisted route. Structural characterizations of all the synthesized compounds were performed by using spectral and elemental analysis. All the synthesized compounds evaluated for their antimicrobial and anticonvulsant activities by using disc diffusion method and maximal electroshock induced seizures (MES) method. It was found that the compounds having potent antimicrobial and anticonvulsant activities.