The diagonals of a rhombus are 16 cm and 12 cm.

All the sides of a rhombus are equal in length.

The diagonals of a rhombus intersect at 90∘">90∘90∘.

The diagonal and the side of a rhombus form right triangles.

$\ln \triangle A O B:$

$A B^{2}=A O^{2}+O B^{2}$

$=8^{2}+6^{2}$

$=64+36$

$=100$

$A B=10 \mathrm{~cm}$

Therefore, the length of each side of the rhombus is $10 \mathrm{~cm}$.