The performance of ethanol distillation is determined by the type of reboiler used in the distillation column. This study aims to determine the effect of differences in diameter and height of internal reboiler tubes, as well as feed content on ethanol distillate concentration and distillation yield. The research was conducted on a batch ethanol distillation process using a rectified distillation device with an internal vertical tubular baffle reboiler using different diameters and tube height, namely 1.5, 1, and 0.5 inches of diameter, and 8, 6, and 4 cm of tube heights. Materials or feeds in this study were ethanol solutions with levels of 10%, 20%, and 30% v/v. The results showed that the highest ethanol distillate content of 97.17% v/v (average) was achieved in the distillation process using an internal reboiler with a diameter of 0.5”, a tube height of 8 cm, and a feed content of 10%. Geometry affected the heat transfer process in the internal reboiler of a distillation device so that it affected the distillation results.Keywords: distillation; ethanol; internal reboiler: performanceA B S T R A KKinerja alat distilasi etanol ditentukan oleh jenis reboiler yang digunakan pada kolom distilasi. Penelitian ini bertujuan untuk menentukan pengaruh perbedaan diameter dan tinggi tabung internal reboiler, serta kadar umpan terhadap kadar etanol distilat dan rendemen distilasi. Penelitian dilakukan pada proses distilasi etanol secara batch menggunakan alat distilasi rektifikasi dengan internal reboiler jenis Vertical Tubular Baffle yang berbeda ukuran diameter dan tinggi tabungnya, yaitu diameter 1,5, 1 dan 0,5 inci, serta tinggi tabung 8, 6 dan 4 cm. Bahan atau umpan pada penelitian ini adalah larutan etanol berkadar 10%, 20% dan 30% v/v. Hasil penelitian didapatkan kadar etanol distilat yang paling tinggi dengan kadar rata-rata 97,17% v/v dicapai pada proses distilasi dengan internal reboiler berukuran diameter 0,5 inci, dan tinggi tabung 8 cm dan kadar umpan 10%. Geometri berpengaruh pada proses perpindahan panas di dalam internal reboiler suatu alat distilasi sehingga berpengaruh terhadap hasil distilasi.Kata kunci: distilasi; etanol; internal reboiler; kinerja