The Dimensional Formula of Coefficient of Viscosity is [ML-1T-1]. This can be explained as follows:

Heading: Introduction
Viscosity is a measure of a fluid's resistance to flow. It is determined by the internal friction of a fluid and is usually measured in units of poise or centipoise. The coefficient of viscosity is a measure of the viscosity of a fluid, and it is defined as the ratio of the shear stress to the rate of shear strain.

Heading: Definition of Coefficient of Viscosity
The coefficient of viscosity can be defined as the measure of the resistance of a fluid to flow under the influence of an external force. It is represented by the Greek letter "eta" (η) and is given by the equation:

η = (F/A) / (dv/dx)

Where,
F = Force applied on the fluid,
A = Area of contact,
dv/dx = Velocity gradient

Heading: Deriving the Dimensional Formula of Coefficient of Viscosity
The unit of force is Newtons (N), the unit of area is square meters (m2), and the unit of velocity gradient is meters per second per meter (m/s/m) or simply meters per second (m/s). Thus, the unit of coefficient of viscosity can be derived as follows:

η = (N/m2) / (m/s)
η = Ns/m2

Now, we know that the dimension of force is [MLT-2], the dimension of area is [L2], and the dimension of time is [T]. Substituting these values, we get:

[Ns/m2] = [MLT-2][L-2][T1]

Simplifying this expression, we get:

[Ns/m2] = [ML-1T-1]

Heading: Conclusion
Hence, the dimensional formula of coefficient of viscosity is [ML-1T-1].