Adsorption of naphtol dye has been done by using humic acid adsorbent taken from Kalimantan peat isolation. This study aims to determine the effect of pH adsorption on naphtol dyes with humic acid taken from Kalimantan peat isolation. Humic acid which is using as an adsorbent to adsorb the naphthol dye solution. The adsorption process was measured using a UV-Vis spectrophotometer to determine the concentration of the adsorbed naphthol dye. The adsorption study from the research results showed that the adsorption of naphtol coloring to humic acid was optimal at pH 2.