For the first time, application of acid-treated coal fly ash as a catalyst for selective dehydration of D-xylose to furfural was investigated in this work. Coal fly ash had been treated with sulphuric acid to promote de-alumination and consequently enhance the silanol concentration in the modified catalyst. This Bronsted acidic catalyst had been effective to convert 85% D-xylose to yield 62% furfural at 170 degrees C. On addition of 35 ppt of NaCl to the system furfural yield was improved to 68%. This promising result in equivalent salinity of sea water might open up possibilities to investigate inexpensive sea water as a replacement of distilled water to improve the product yield. The catalyst was stable enough to sustain minimum of 6 cycles of run. Apart from the abundant availability and cheap price of fly ash, utilizing it for heterogeneous catalysis drives to mitigate disposal problems of fly ash to partial extent. The dual advantages make the system eco-friendly.