Ticarcillin is a carboxypenicillin. It can be sold and used in combination with clavulanate as ticarcillin/clavulanic acid. Because it is a penicillin, it also falls within the larger class of β-lactam antibiotics. Its main clinical use is as an injectable antibiotic for the treatment of Gram-negative bacteria, particularly Pseudomonas aeruginosa and Proteus vulgaris. It is also one of the few antibiotics capable of treating Stenotrophomonas maltophilia infections.

It is provided as a white or pale-yellow powder. It is highly soluble in water, but should be dissolved only immediately before use to prevent degradation.

It was patented in 1963.

Ticarcillin's antibiotic properties arise from its ability to prevent cross-linking of peptidoglycan during cell wall synthesis, when the bacteria try to divide, causing cell death.^{[citation needed]}

Ticarcillin, like penicillin, contains a β-lactam ring that can be cleaved by β-lactamases, resulting in inactivation of the antibiotic. Those bacteria that can express β-lactamases are, therefore, resistant to β-lactam antibiotics. Due at least in part to the common β-lactam ring, ticarcillin can cause reactions in patients allergic to penicillin. Ticarcillin is also often paired with a β-lactamase inhibitor such as clavulanic acid (co-ticarclav).^{[citation needed]}

In molecular biology, ticarcillin is used to as an alternative to ampicillin to test the uptake of marker genes into bacteria. It prevents the appearance of satellite colonies that occur when ampicillin breaks down in the medium. It is also used in plant molecular biology to kill Agrobacterium, which is used to deliver genes to plant cells.

Ticarcillin is not absorbed orally, so must be given by intravenous or intramuscular injection.

However Timentin contains clavulanate unlike Ticar