Squaric acid (SA) has been investigated as a readily available organic anode material in rechargeable lithium batteries. To overcome both conductivity and dissolution problems related to organic compounds, SA was conformally coated with conductive polyaniline through a facile in situ chemical polymerization route. Polyaniline-coated SA exhibits a stable high capacity of 394 mAhg(-1) after 100 cycles at 100 mAg(-1) in lithium batteries. At 1 Ag-1 current density, polyaniline-coated SA (PANI-SA) shows long cycle life over 1000 cycles with 96.9% retention of initial reversible capacity. The reversible Li+ storage property of SA is revealed through ex situ NMR characterization.