|Amount per unit||
50 (SS1, SSHD), 100 (SS2, SS:NE Tourist, Easy and Serious SS1 and HD), 50 (SSDD)
In every game it appears in, Napalm is a medium-sized orange tank with a logo and some attachment pipes on it.
The amount of Napalm depends on the game it is in. In Normal, Hard and Mental, Serious Sam: The Second Encounter and Serious Sam HD, it gives the player 50 Napalm units when picked up, while in Tourist, Easy and Serious it gives the player 100 Napalm units per pickup. Serious Sam: Next Encounter Napalm gives 100 units per pickup, while Serious Sam: Double D's Napalm pickup gives 50 units of Napalm ammo.
Serious Sam: Next Encounter contains two Napalm variants: Nitrogen and Laughing Gas. Nitrogen makes the XOP Gas Gun behave the same as normal napalm does, but instead freezes the enemy when it is killed. Laughing Gas will stun enemies by making them laugh, letting the player continue hitting them with Laughing Gas or kill the enemy with another weapon.
- Napalm is quite common in Serious Sam: The Second Encounter and Serious Sam HD, which lets the player use the XOP Flamethrower often.
- Laughing Gas is quite rare, and is usually found only in secrets.