  Recently Gordon and McIntosh introduced the third order mock theta function
$\xi(q)$ defined by $$
\xi(q)=1+2\sum_{n=1}^{\infty}\frac{q^{6n^2-6n+1}}{(q;q^6)_{n}(q^5;q^6)_{n}}. $$
Our goal in this paper is to study arithmetic properties of the coefficients of
this function. We present a number of such properties, including several
infinite families of Ramanujan--like congruences.
