The white rot fungus, Ganoderma boninense is the main causal agent of basal stem rot disease in oil palm plantations in South-east Asia especially Malaysia and Indonesia. Despite serious attention given the fungus, knowledge on the pathogen-oil palm interaction especially from the molecular and biochemical aspects is still inadequate to provide a better understanding on the disease. In this study, an 1161 bp of full-length cDNA encoding a Hog1-type MAPK was obtained from G. boninense. Based on the multiple sequence alignment, the conserved motif TGY (novel activation loop motif), N-terminal-conserved domain, HRDLKPN and the C-terminal-conserved domain, TRWYRAP were found in G. boninense Hog1 MAPK. Results of salinity stress assay indicated that G. boninense growth was slower on media containing 0.4 M NaCl and could not survive on media containing 1.0 M NaCl. Real-time quantitative PCR analysis showed that GbHog1 MAPK transcript was consistently upregulated to nearly 4.0 folds after 2 hr of exposure to 0.4 M NaCl. This study provides a preliminary understanding on the involvement of GbHog1 MAPK in salinity stress response. Identification of GbHog1 MAPK could also lead to understanding of the involvement of G. boninense MAPK in pathogenicity as reported in several plant pathogenic fungi.