Acid mine/rock drainage (AMD/ARD) is a serious environmental problem which occurs when metal sulfides (chiefly pyrite) get oxidized in the presence of oxygen. Metal sulfide dissolution results in metal-rich and extreme acidic solutions. Acidophilic microorganisms are believed to play a key role in metal sulfide oxidation and dissolution. The acidophilic archaea Ferroplasma receive considerable interest with respect to their special physiological characteristics, e.g. extreme acidophiles often detected in AMD and cell wall-lacking. We studied surface properties of F. acidiphilum DSM 28986 by attenuated Total Reflection-Fourier Transformed Infra-Red (ATR-FTIR) spectroscopy and microbial adhesion to hydrocarbon (MATH) techniques. In addition, extracellular polymeric substances (EPS) were characterized by fluorescence lectin-binding analysis (FLBA) and conventional colorimetric analysis. Results showed that: 1) cell hydrophilicity/hydrophobicity and surface components varied among different growth conditions, as revealed by MATH and ATR-FTIR, respectively; 2) cells selectively adhered to mineral surfaces and showed maximum attachment to pyrite of approx. 50% within 30 min; 4) EPS synthesis by F. acidiphilum DSM 28986 was influenced by growth substrates; and 5) tightly-bound EPS were composed of carbohydrates and proteins. In contrast, loosely-bound EPS are mainly characterized as carbohydrates. Monosaccharides like glucose, fucose, arabinose, galactose, mannose, and sialic acid were detected in the EPS of F. acidiphilum DSM 28986. This study provides first insight into surface characterization of the cell wall-lacking archaeon F. acidiphilum and facilitates the understanding of interactions of this organism with metal sulfides and other acidophiles in acid environments e.g. AMD.