The electronic structure ofconjl!gated polymer (n-polyme/) is calculated using Linear Combination 0/ Atomic Orbital (LCAO). LCAO is a quantum supefposition technique to calculate energy level ofmolecl/lar orbital (MO). This article discusses the electronic structure ofnaphthalene andpolyacetylene (PA). Naphthalene and its derivative are aromatic molecules that are widely used as a hole transport layer in most organic light emilling diode (OLED) applications. In calculating energy level, the basic electronic molecule/rome work and Secular determinant must be determined. The band energy ofPA is calculated using Ritz Method where H;; determines the interaction ofelectrons in an isolated 2pz orbital while Sy measures the overlapping betvveen basis jill1ction. ln microscopic level, the important parameters are Highest Occupied Molecular Orbital (HOMO) which is equivalent with conduction band and Lowest Unoccupied Moleclilar Orbital (LUMO) which is eqUivalent with valence band. For Naphthalene, the positive and negative changing in coefficient ofLCAO ShOH'S the changing in lVavefunction in every monomer unit and its effects on the electronic properties. In polyacetylene, Fermi Energy levels lay between -0.9 eV and -l. leV.