Peat sorbents modified with iron, nitrogen containing functional groups and iron humate were prepared for adsorption of arsenic compounds. Synthesis of modified peat (I) was based on iron hydroxide (III) precipitation onto peat. A dispersion of Fe(OH)3 was mixed in homogenized peat. After filtration, reaction product was rinsed with distilled water and dried. However synthesis of modified peat (II) was based on peat saturation with iron salts. To prepare nitrogen functional group containing peat sorbent peat was mixed with sodium hydroxide solution. After that epichlorhydrine was added to the reaction mixture and the contents were heated at 50 ˚ C with continuous intensive stirring. After that diethyl amine was added to the suspension and left overnight. The obtained product was filtered, washed with distilled water, acetone and dried. For synthesis of iron humate sodium hydroxide solution was poured onto peat and it was left for 24 h. After that the obtained suspension was filtered and filtrate was neutralized. Iron chloride solution was added to the filtrate. The obtained precipitates were filtered, washed with distilled water and dried. Scanning electron microscope pictures show the differences in peat structure of raw material and peat samples modified with iron. Iron content in modified peat samples were higher than in raw peat material, indicating that modification had occurred. Adsorption of arsenic compounds onto peat and on iron modified peat sorbents was investigated. The highest sorption capacity was observed using iron modified peat sorbents. Using iron modified peat sorbents, adsorption of arsenic compounds was investigated as a function of pH. It can be suggested that adsorption is influenced by the method of modification and iron content in peat. Adsorption at different pH values was dependent of arsenic form present in solution. The results of this study can be used for new peat sorbent development which could be used for drinking water purification from arsenic compounds.