Composite materials are emerging chiefly in response to fulfill demands from technology due to rapidly advancing activities in aircrafts, aerospace and automotive industries. Natural fibers have recently attracted the attention of scientists and technologists because of the advantages that these fibers provide over conventional reinforcement materials, and the development of bio fiber composites has been a subject of interest for the past few years. The present work focuses on investigation of hardness value of coir fiber/epoxy resin composite at 10%, 15% and 20% volume fractions of coir fiber and different fiber lengths 10 mm, 20 mm and 30 mm. Initially alkalization process consisted of immersing coir fibers in a 1% (v) NaOH aqueous solution for 6 hrs to improve physical properties of coir fiber. The test specimens were prepared and tested according to ASTM standards for micro hardness testing. The experimental results shows that with increase in volume fraction and fiber length, the hardness of composite increases and better hardness value is obtained at 20% volume fraction and 20 mm fiber length.