Yanti, Pepi HelzaJamarun, NovesarArief, Syukri2014-05-212014-05-212014-05-21978-602-18936-0-9wahyu sari yenihttp://repository.unri.ac.id/xmlui/handle/123456789/6266Synthesis Precipitated Calcium Carbonate have done using lisin as source of amino acid with modification of caustic soda method. The limestone are first calcinated by XRF to analysis composition of limestone. The result showed CaO of limestone 55,26%. Analysis using FT-IR proved a pure crystal without contain lisin. Analysis using XRD showed optimum peak 2θ = 29,48300 .The particle size of lisin 0,05 M 68,56 nm with 88.21% calsit and 11.79% vaterit while particle size of Lisin 0.150 M 57.13 nm with 80.12% calsit and 19.89% vaterit. Based on our research proved that lisin can be used as directing agent to produce PCC. Key words: calcination, caustic soda , directing agent, lisin, PCCencalcinationcaustic sodadirecting agentlisinPCCUR-Proceedings