Direct C-H arylation of thieno[2,3-b]thiophene is reported under Pd(OAc)2/n-Bu4NBr catalysis and provides rapid entry into the first examples of 2,5-diaryl thienothiophenes. The reaction works well with either electron-deficient or electron-rich halo-arenes, giving satisfactory yields of diarylation products. Novel push-pull thienothiophenes bearing electron-deficient aryl groups (λmax 318-373 nm and λcut-off 430 nm) are potentially interesting for their photonic properties.