A Baire space $B$ and a compact space $K$ satisfy the Namioka property $N(B,K)$ if for every separately continuous function $f: B\times K\to R$ there is a dense set $A\subset B$ such that $f$ is jointly continuous at each poin of $A\times K$. Its proved that $N(B,K)$ and $N(B,L)$ imply $N(B,K\times L$. It follows in particular that the class of co-Namioka compact spaces is stable under (arbitrary) product.
@article{hal-00373444,
author = {Bouziad, Ahmed},
title = {The class of co-Namioka compact spaces is stable under product},
journal = {HAL},
volume = {1996},
number = {0},
year = {1996},
language = {en},
url = {http://dml.mathdoc.fr/item/hal-00373444}
}
Bouziad, Ahmed. The class of co-Namioka compact spaces is stable under product. HAL, Tome 1996 (1996) no. 0, . http://gdmltest.u-ga.fr/item/hal-00373444/