ABSTRAK Minyak sereh dapur (lemongrass oil) merupakan salah satu jenis minyak atsiri terpenting yang dihasilkan di Negara Indonesia. Minyak atsiri dari minyak sereh dapur memiliki aktivitas antioksidan. Rancangan penelitian yang digunakan adalah Rancangan Acak Lengkap (RAL) dengan pola faktorial yang terdiri atas 2 faktor. Faktor I adalah Bagian tanaman (B) yang terdiri atas 3 taraf yaitu: B1: (batang), B2 : (Daun), B3 : (Daun dan batang). Faktor II adalah Perlakuan pemurnian (P) terdiri atas dua taraf yaitu: P1 : (sebelum pemurnian) , P2 : (sesudah pemurnian). Setiap perlakuan diulang sebanyak tiga (3) kali sehingga terdapat 18 perlakuan. Hasil penelitian menunjukkan bahwa Bagian tanaman berpengaruh sangat nyata terhadap daya reduksi, indek bias dan bobot jenis minyak sereh dapur. Perlakuan pemurnian berpengaruh sangat nyata terhadap aktivitas antioksidan, indek bias, dan bobot jenis minyak sereh dapur. Interaksi antara kedua perlakuan berpengaruh sangat nyata terhadap indek bias dan bobot jenis minyak sereh dapur. Kadar sitral tertinggi diperoleh dari minyak sereh dapur bagian batang sesudah pemurnian 89,90 %. 5. Perlakuan terbaik berdasarkan uji aktivitas antioksidan dan daya reduksi diperoleh pada kombinasi perlakuan campuran batang dan daun setelah pemurnian (B3P2) dengan kadar sitral 89,19%, aktivitas antioksidan 59,27 %, bobot jenis 0,9200 % (memenuhi standar SNI), dan kelarutan dalam etanol keruh. Kata kunci : olahan sereh dapur, proses pemurnian, dan aktivitas antioksidan Lemongrass (Cimbopogon citratus) oil is one of the most important essential oils produced in Indonesia. This essential oil has its antioxidant activity. Therefore, a completely randomized design was used which consisted of two factors. The first factor was the part of plant (B), consisting three stages: B1 (rod), B2 (leaf), and B3 (leaf and rod). The second factor was purification treatment (P) consisting two stages: P1 (before the purification) , and P2 :(after the purification). Every treatment was repeated three times, so that there were 18 treatments. The result of the research indicated that the part of plant significantly affected the reduction energy, refraction index, and the amount of lemongrass oil. The purification treatment completely affected antioxidant activity, refraction index and the amount lemongrass. Consequently, these two treatments significantly affected the refractive index and the amount of lemongrass oil. The highest citral intensity was obtained from lemongrass rod and after purification which was around 89,90 %. An ideal treatment based on antioxidant test and reduction power was the combination treatments of rod and purification leaf (B3P2) with 89,19% citral, 59,27 % antioxidant activity, 0,9200% in size, and low ethanol solubility. All of these values met the ISO standard. Key words: Lemongrass process, purification treatment and antioxidant activity.