Biocorrosion　is　also　known　as　microbiologically　influenced　corrosion　(MIC).　Most　anaerobic　MIC　cases　can　be　classified　into　two　major　types.　Type　I　MIC　involves　non-oxygen　oxidants　such　as　sulfate　and　nitrate　that　require　biocatalysis　for　their　reduction　in　the　cytoplasm　of　microbes　such　as　sulfate　reducing　bacteria　(SRB)　and　nitrate　reducing　bacteria　(NRB).　This　means　that　the　extracellular　electrons　from　the　oxidation　of　metal　such　as　iron　must　be　transported　across　cell　walls　into　the　cytoplasm.　Type　II　MIC　involves　oxidants　such　as　protons　that　are　secreted　by　microbes　such　as　acid　producing　bacteria　(APB).　The　biofilms　in　this　case　supply　the　locally　high　concentrations　of　oxidants　that　are　corrosive　without　biocatalysis.　This　work　describes　a　mechanistic　model　that　is　based　on　the　biocatalytic　cathodic　sulfate　reduction　(BCSR)　theory.　The　model　utilizes　charge　transfer　and　mass　transfer　concepts　to　describe　the　SRB　biocorrosion　process.　The　model　also　includes　a　mechanism　to　describe　APB　attack　based　on　the　local　acidic　pH　at　a　pit　bottom.　A　pitting　prediction　software　package　has　been　created　based　on　the　mechanisms.　It　predicts　long-term　pitting　rates　and　worst-case　scenarios　after　calibration　using　SRB　short-term　pit　depth　data.　Various　parameters　can　be　investigated　through　computer　simulation.　(C)　2016　Elsevier　B.V.　All　rights　reserved.