The present invention relates a process of producing a lightweight eco-friendly hollow masonry block comprises of the following steps: Preparing the composition of hollow masonry block which comprises of a binder, fine aggregate and coarse aggregate wherein: Binder consisting weight ratio (3:7) of palm oil clinker powder and cement; Fine aggregate consisting manufactured sand (M-sand); and Coarse aggregate consisting weight ratio of palm oil clinker and crushed granite. Further Characterised by: Mixing binder, fine aggregate and coarse aggregate simultaneously at room temperature for a duration range of 3-5 min to form a hollow masonry block consisting of the mix ratio of (1:4.4:1.6) using fineness modulus method of concrete mix; Adding 176 kg/m3 water and mixing with the hollow masonry block mix preferably for 5-8 min to obtain a homogenous mixture; Conducting a slump test to ensure that the mixture is dry; Casting and moulding masonry block mix to form hollow masonry block; Covering and storing hollow masonry block (6) preferably at temperature range from 28°C to 32°C and relative humidity preferably range from 60-80% for 28 days.