The phrase "a complicated process which" is correct and usable in written English.
It can be used when describing a process that has multiple steps or elements that make it difficult to understand or execute.
Example: "The project involves a complicated process which requires careful planning and coordination among team members."
Alternatives: "a complex procedure that" or "an intricate method which".
Cell movement is a complicated process, which requires the intracellular orchestration of numerous biochemical and cell-biological events.
Four friends – Nick Drewe, Andy Thelander, Jack Murphy and Tom Knox – managed to count several thousand listeners' votes via scraping data from Twitter and Facebook, a complicated process which is explained here.
They were first introduced in 1909 by Hugh Lowther, the 5th Earl of Lonsdale, and are created using a complicated process which can take several weeks.
Web development can be a complicated process which can go on too long because so much of the time is spent on really poor communication and mis-understandings.
Establishing the advantages and disadvantages of the transport rules of CIM and SMGS is a complicated process which is affected by several factors.
The only imaginable way to continue the existing ban beyond 2015 would be explicit legislation to this effect - a complicated process which might even run into constitutional difficulties and fail to clear the hurdle of the Constitutional Court.
"The unique nature of this panel, and the forensic nature of the investigations that have taken place, have made for a very complicated process which is now at a conclusion.
"It's a very complicated process, which involves not just your riding and results, but interviews and such.
Cell wall biogenesis is a very complicated process which incorporates not only multiple gene families directly involved in the polysaccharide biosynthesis and the remodeling of different cell wall components, but also structural proteins involved in cell wall assembly and rearrangement.
However, it is a very complicated process which cannot be described analytically.
The calculation of GWP is an extremely complicated process which involves interactions between surface and atmosphere such as atmospheric radiative transfer and atmospheric chemical reactions.
