NOVELTY - Isolated polypeptide having cellulolytic enhancing activity, comprising e.g. (a) a polypeptide having at least 90% sequence identity to the mature polypeptide of SEQ ID NO: 2 or SEQ ID NO: 4 and (b) a polypeptide encoded by a polynucleotide that hybridizes under at least very high stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 1 or SEQ ID NO: 3 or its cDNA sequence or full-length complement, is new, where sequences not defined here may be found at ftp://ftp.wipo.int/pub/published-pct-sequences/publication.    USE - The isolated polypeptide is useful for saccharifying the cellulosic material for producing a fermentation product (claimed) such as fuel, preferably ethanol, n-butanol, isobutanol, biodiesel and jet fuel, and/or platform chemicals, preferably acids, alcohols, ketones, gases and oils.    ADVANTAGE - The isolated polypeptide provides the fermentation product with increased efficiency in a cost-effective manner.    DETAILED DESCRIPTION - Isolated polypeptide: either having cellulolytic enhancing activity, comprising (a) a polypeptide having at least 90% sequence identity to the mature polypeptide of SEQ ID NO: 2 or SEQ ID NO: 4, (b) a polypeptide encoded by a polynucleotide that hybridizes under at least very high stringency conditions with the mature polypeptide coding sequence of SEQ ID NO: 1 or SEQ ID NO: 3 or its cDNA sequence or full-length complement, (c) a polypeptide encoded by a polynucleotide having at least 90% sequence identity to the mature polypeptide coding sequence of SEQ ID NO: 1 or SEQ ID NO: 3 or its cDNA sequence, (d) a variant of the mature polypeptide of SEQ ID NO: 2 or SEQ ID NO: 4 comprising a substitution, deletion, and/or insertion at one or more positions, or (e) a fragment of the polypeptide of (a)-(d) that has cellulolytic enhancing activity; or having a catalytic domain comprising (a1) a catalytic domain having at least 90% sequence identity to amino acids 20-223 of SEQ ID NO: 4, (b1) a catalytic domain encoded by a polynucleotide that hybridizes under at least very high stringency conditions with nucleotides 58-1004 of SEQ ID NO: 3 or its cDNA sequence or its full-length complement, (c1) a catalytic domain encoded by a polynucleotide having at least 90% sequence identity to nucleotides 58-1004 of SEQ ID NO: 3 or its cDNA sequence, (d1) a variant of amino acids 20-223 of SEQ ID NO: 4 comprising a substitution, deletion, and/or insertion at one or more positions, or (e1) a fragment of the catalytic domain of (a1)-(d1) that has cellulolytic enhancing activity; or having a carbohydrate binding module operably linked to the catalytic domain in which the binding domain comprises (a2) a carbohydrate binding module having at least 90% sequence identity to amino acids 255-292 of SEQ ID NO: 4, (b2) a carbohydrate binding module encoded by a polynucleotide that hybridizes under at least very high stringency conditions with nucleotides 1098-1332 of SEQ ID NO: 3 or its cDNA sequence or full-length complement, (c2) a carbohydrate binding module encoded by a polynucleotide having at least 90% sequence identity to nucleotides 1098-1332 of SEQ ID NO: 3 or its cDNA sequence, (d2) a variant of amino acids 255-292 of SEQ ID NO: 4 comprising a substitution, deletion, and/or insertion at one or more positions, or (e2) a fragment of the carbohydrate binding module of (a2)-(d2) that has binding activity, is new, where sequences not defined here may be found at ftp://ftp.wipo.int/pub/published-pct-sequences/publication. INDEPENDENT CLAIMS are included for:    (1) an isolated polynucleotide encoding the polypeptide;    (2) a recombinant host cell comprising the polynucleotide operably linked to one or more control sequences that direct the production of the polypeptide;    (3) a transgenic plant or its part or plant cell transformed with a polynucleotide encoding the polypeptide;    (4) producing a mutant of a parent cell, comprising inactivating the polynucleotide encoding the polypeptide, which results in the mutant producing less of the polypeptide than the parent cell;    (5) a double-stranded inhibitory RNA (dsRNA) molecule comprising a subsequence of the polynucleotide, where optionally the dsRNA is a small interfering RNA or a micro RNA molecule;    (6) inhibiting the expression of a polypeptide having cellulolytic enhancing activity in a cell, comprising administering or expressing the dsRNA molecule to the cell;    (7) an isolated polynucleotide encoding a signal peptide comprising or consisting of amino acids 1-17 of SEQ ID NO: 2 or amino acids 1-19 of SEQ ID NO: 4;    (8) producing a protein, comprising cultivating a recombinant host cell comprising a gene encoding a protein operably linked to the polynucleotide, where the gene is foreign to the polynucleotide encoding the signal peptide, under conditions conducive for production of the protein;    (9) degrading a cellulosic material, comprising treating the cellulosic material with an enzyme composition in the presence of the polypeptide;    (10) producing a fermentation product, comprising saccharifying a cellulosic material with an enzyme composition in the presence of the polypeptide, fermenting the saccharified cellulosic material with one or more fermenting microorganisms to produce the fermentation product, and recovering the fermentation product from the fermentation;    (11) fermenting a cellulosic material, comprising fermenting the cellulosic material with one or more fermenting microorganisms, where the cellulosic material is saccharified with the enzyme composition in the presence of the polypeptide;    (12) a whole broth formulation or cell culture composition comprising the polypeptide; and    (13) the preparation of isolated polypeptide.