The quaternary chalcogenides SnBi4-xTe3+ySe4-z and PbBi4-xTe3-ySe4-z have been prepared and found to possess orthorhombic structure. The chemical composition of materials is confirmed by EDX. SnBi4-xTe3+ySe4-z and PbBi4-xTe3-ySe4-z exhibit a low resistivity 0.0055 ohm cm and 0.1665 ohm cm at room temperature and carrier concentration 7.15 x 10(18) and 1.97 x 10(16) cm(-3) respectively. The Hall measurements show n-type behaviour with mobility of carrier 87 and 2534 M-2/V, and band gap by diffuse reflectance are found to be 4.37 eV and 3.98 eV for SnBi4-xTe3+ySe4-z and PbBi4-xTe3-ySe4-z respectively.