Aims:  A new cellobiohydrolase (CBH) gene (cbh3) from Chaetomium thermophilum was cloned, sequenced and expressed in Pichia pastoris. Methods and Results:  Using RACE‐PCR, a new thermostable CBH gene (cbh3) was cloned from C. thermophilum. The cDNA of the CBH was 1607 bp and contained a 1356 bp open reading frame encoding a protein CBH precursor of 451 amino acid residues. The mature protein structure of C. thermophilum CBH3 only comprises a catalytic domain and lacks cellulose‐binding domain and a hinge region. The gene was expressed in P. pastoris. The recombinant CBH purified was a glycoprotein with a size of about 48·0 kDa, and exhibited optimum catalytic activity at pH 5·0 and 60 °C. The enzyme was more resistant to high temperature. The CBH could hydrolyse microcrystalline cellulose and filter paper. Conclusions:  A new thermostable CBH gene of C. thermophilum was cloned, sequenced and overexpressed in P. pastoris. Significance and Impact of the Study:  This CBH offers an interesting potential in saccharification steps in both cellulose enzymatic conversion and alcohol production.