The aim of this research was to study the effect of cocoa butter addition on stability, irritation effect, and sensory properties of hair shampoo. The hair shampoo formula referred to the Rosniati formula (2015) modified by the addition of cetyl alcohol, glycerin, novenmer, stearic acid and 2.5% SLS. The new formulas were made by adding respectively 0%, 1.0%, and 1.5% cocoa butter into the formula. The results showed that the addition of 1.0% cocoa butter to the shampoo formula had the highest viscosity and sensory properties were better compared to the two other formulas, especially in terms of consistency, color, and foam. In general, the three formulas were stable, pH was standard, and there was no eye-irritation effect in the clinic test. However, they caused light irritation effect to the rabbit skin with the IIKP values of 0.361, 0.417, and 0.403 for formulas A, B, and C, respectively.Keywords: cocoa butter, hair shampoo, and shampoo formulaABSTRAK. Tujuan dari penelitian ini adalah untuk mengetahui pengaruh penambahan lemak kakao terhadap kestabilan, efek iritasi, dan sifat sensori sampo rambut. Formula sampo rambut mengacu ke formula Rosniati, (2015) yang dimodifikasi dengan penambahan setil alkohol, gliserin, novenmer, asam stearate dan SLS 2.5 %. Tiga formula baru dibuat masing-masing menggunakan lemak kakao 0 %, 1.0 %, dan 1,5 % dalam formula. Hasil penelitian menunjukkan bahwa penambahan lemak kakao 1.0 % ke dalam formula sampo mempunyai nilai viskositas yang paling tinggi dan nilai sensori yang lebih baik dibandingkan dengan kedua formula lainnya, dalam hal konsistensi, warna dan busa. Secara keseluruhan semua sediaan formula sampo mempunyai sifat stabil, pH sesuai standar dan hasil uji klinis, menunjukkan bahwa tidak menimbulkan efek iritasi terhadap mata, tetapi menimbulkan iritasi ringan terhadap kulit kelinci dengan nilai IIKP berturut-turut 0.361, 0.417, dan 0.403 untuk formula A, B, dan C.Kata kunci : lemak kakao, sampo rambut, dan formula sampo