Qualitative hazard assessment is part of the detailed risk analysis of chemical process industries and a hazard and operability (HAZOP) study is the best technique to carry out this step. It is a systematic study conducted by a team of experts of different disciplines to identify and assess hazards using brainstorming discussion of deviation In operational parameters from normal/standard conditions. This study needs high levels of expertise and substantial time commitments. The various steps involved in any typical HAZOP (application of deviation, cause finding, and consequence analysis of each and every line and equipment) need a sustained high level of mental performance and alertness for a long span of time, but the repetitious nature of these steps inevitably generates a feeling of drudgery and mental fatigue, even exhaustion. This may not only reduce the effectiveness of HAZOP, but even render it incomplete or erroneous. This paper is devoted to a discussion about the factors that have direct influence on the efficiency, effectiveness and reliability of such studies. It also suggests an optimal approach to HAZOP study procedures (optHAZOP) based on the utilization of an already developed information base. The optHAZOP technique reduces the mental execution load of experts by a half, and thus provides more time to study typical hazardous units and conceptualize better control strategies. This technique takes around 45% less time than that of the conventional HAZOP study procedure (estimated using CPM networking and time analysis of different steps of study) with better efficiency and effectiveness.