Preparation of proteins from salt-gland-enriched tissues of mangrove plant is necessary for a systematic study of proteins involved in the plant’s unique desalination mechanism. Extraction of high-quality proteins from the leaves of mangrove tree species, however, is difficult due to the presence of high levels of endogenous phenolic compounds. In our study, preparation of proteins from only a part of the leaf tissues was required, rendering extraction even more challenging. By comparing several extraction methods, we developed a reliable procedure for obtaining sufficient proteins from salt gland-enriched tissues of the mangrove species Avicennia officinalis. Protein extraction was markedly improved using a phenol-based extraction method. Despite the lower protein yield obtained, one-dimensional protein gel profiles with greater resolution could be obtained, with more than twice the number of proteins detected when 1D-LC-MS/MS analyses were compared. Further analysis of proteins that were solely present in each extraction method favoured the phenol-based extraction. Phenol-based extracts contained nearly 10 times more solely-detected proteins than those were detectable in the extracts without using phenol. The protocol established could thus be applied for downstream high-throughput proteomic analyses involving LC-MS/MS or equivalent.