PTK may refer to:

• Pairwise Transient Key, a key in the IEEE 802.11i WPA2 specification
• Phi Theta Kappa, an international honor society
• Phototherapeutic keratectomy, laser eye surgery
• Pilotiruemyi Transportny Korabl Novogo Pokoleniya (PTK NP, lit. "New Generation Piloted Transport Ship"), a Roscosmos program to develop a reusable spacecraft
• Portal Three Kingdoms, a Magic: The Gathering card set
• Post and Telecom of Kosovo
• Protein Tyrosine Kinase, an enzyme
• PTK Toolkit, a C++ toolkit for creating MacOS and Windows cross-platform games
• Oakland County International Airport, a county-owned public-use airport located in Waterford, Michigan with IATA Code PTK
• P, T and K, the most common voiceless plosive consonants across all languages