Let
$\mathcal {P}_s(n)$
denote the nth s-gonal number. We consider the equation
$$ \begin{align*}\mathcal{P}_s(n) = y^m \end{align*} $$
for integers
$n,s,y$
and m. All solutions to this equation are known for
$m>2$
and
$s \in \{3,5,6,8,20 \}$
. We consider the case
$s=10$
, that of decagonal numbers. Using a descent argument and the modular method, we prove that the only decagonal number greater than 1 expressible as a perfect mth power with
$m>1$
is
$\mathcal {P}_{10}(3) = 3^3$
.