Bottom ash is a hazardous by-product from coal based thermal power plants. In this study fine aggregate in concrete mix has been replaced with bottom ash and Polypropylene fibre is additionally used to enhance the strength characteristics of concrete. The concrete mix design is made for concrete hollow block whose grade is B(3.5). The mechanical properties were compared with control mix and it was found that the optimal combination of polypropylene fibre as 0.5% of weight of cement, which is more sufficient to have economically strong hollow blocks. Compressive strength was compared by testing mixer block without bottom ash and polypropylene fibre of size 400 X 200 X 200 mm. Results showed that there was considerable amount of strength for blocks with bottom ash as replacement for fine aggregate.