How many countries have a hydrogen bomb?

Answer 1

The US, Russia, the United Kingdom, France, China, India, and Pakistan are known to have thermonuclear weapons ("hydrogen bombs"). North Korea has tested fission cores powerful enough to initiate a deuterium-tritium fusion reaction, and it's believed (though it's not known with certainty) that they have a (probably small) stockpile of thermonuclear weapons.

So, that's 7 for sure, 8 almost certainly, and then there's a 9th:

Israel certainly has the technology level and resources required to construct a thermonuclear weapon. However, Israel has never officially confirmed that they have such weapons, and they are a signatory to the Nuclear Non-Proliferation Treaty (though it's generally suspected that they either have, or could in very short order construct, thermonuclear devices).

In addition, the US has nuclear weapons physically stored in Belgium, Germany, Italy, the Netherlands, and Turkey. The US formerly had thermonuclear devices in Canada, Greece and South Korea as well, though these have now been removed. The breakup of the USSR left some of its weapons in Belarus, Kazakhstan, and Ukraine, but these have likewise now been transferred back to Russia.

South Africa at one time had six nuclear weapons, but I believe these were fission ("atomic bomb") weapons and not fusion ("hydrogen bomb") weapons and they've since been disassembled anyway.

Answer 2

There are currently nine countries known to possess hydrogen bombs: the United States, Russia, China, the United Kingdom, France, Israel, India, Pakistan, and North Korea.