The physicochemical properties of pharmacological molecules have a tremendous effect on safety and efficacy. Poor physicochemical properties can often make it hard to set up a reliable structure-activity relationship (SAR) with no prominent efficacy in preclinical and clinical models. This can lead to more variability in capability and higher drug development costs in the entire development process, and in the worst case, even to stop the clinical trials in the later period. Understanding the basic physicochemical properties makes it possible to separate and untangle investigational observations hence poor molecular properties can be changed or fixed during the design phase. This makes it more likely that the molecule will make it through the long and difficult development process. The decline in innovator pharmacotherapeutics number registrations decline each year and the industry is under even more pressure than in the past to speed up the drug development process. This reduces the length of time required for development and introduces innovative pharmaceutical products. To do this, it is imperative to proceed with an organised approach and act appropriately the first time. The current chapter aims to focus on the important physicochemical properties of the selected molecule, along with how those properties are evaluated and implicated in both discovery enablement and final dosage form development.