This Test Guideline (TG) describes a harmonised procedure to determine the Volume Specific Surface Area (VSSA) of powdered solid manufactured nanomaterials (MNs). The VSSA (in m2/cm3) of a material is calculated by multiplying its mass specific surface area (in m2/g) with its skeletal density (in g/cm3). The determination of the external and internal (mass) specific surface area (SSA) of powdered solid MNs is done by the Brunauer, Emmett and Teller (BET) method. This TG also provides instructions on how to determine the skeletal density (ρ) of the MN by gas pycnometry.