Synthesizing a material with the desired polymorphic phase in a chemical vapor deposition (CVD) process requires a delicate balance among various thermodynamic variables. In this presentation, I will discuss the CVD growth of the transition metal dichalcogenides (TMDCs namely MoS2 and WSe2. To begin with, I will present the conventional way of growing MoS2 followed by a novel methodology to synthesize phase selective MoS2 in a well-defined sword-like geometry having lengths up to 120 μm, uniform width of 2–3 μm and thickness of 3-7 nm. Characteristic signatures such as significant changes in the low-frequency Raman modes, increasing intensity of second harmonic signals with an increasing number of layers, and the presence of a middle atom (Molybdenum) in the hexagonal stacking arrangement as revealed by high-resolution transmission electron microscopy conclusively established the rhombohedral (3R)-phase of the material. Besides, helicity-resolved photo luminescence (HRPL) and polarized resolved photoluminescence (PRPL) were performed for this as grown 3R-phase MoS2. A high degree of circular dichroism ∼of 58% at 100 K and a degree of valley coherence ∼of 70% at 80 K signify the grown 3R- MoS2 could be to study the valley physics and develop devices. A field effect mobility of 40 cm2/V-s and Ion/Ioff ratio of ∼106 further confirms the electronic-grade standard of this 3R-phase MoS2. Further, growth substrate affects the optical quality of the grown TMDCs as investigated by growing MoS2 on three different substrates such as Si, SiO2/Si and sapphire. Finally I will present the results on the growth of another TMDC i.e. WSe2. Synthesis of WSe2 requires high temperature and reducing gas like hydrogen. We found that concentration of the H2 plays key role in achieving large single crystal domains of WSe2.