The invention relates to an apparatus for the analysis of a fluid which is present in a line or in a container. It can e.g. be a gas flow in a gas line. The apparatus has an optoelectronic apparatus for the optical analysis. The optoelectronic apparatus itself includes at least two housing parts having housing flanges for flanging the apparatus to a wall of the line or of the container so that the housing parts are disposed opposite one another, a light transmitter and a light receiver which define an optical measurement path between them within the line or the container and an evaluation device. A temperature sensor for detecting the fluid temperature and/or a pressure sensor for detecting the fluid pressure is/are provided beside the optoelectronic apparatus. To provide an improved apparatus for the analysis of a fluid with which temperature and/or pressure can be detected in a simple and in particular inexpensive manner, it is proposed that, for detecting the fluid temperature or fluid pressure in the region of the optical measurement path (33), the temperature measuring apparatus (57) is held extending parallel to the optical measurement path (33) within the line (13) or the container via a spacer (52) or a dynamic pressure pipe (54) of the pressure measuring apparatus (59) and the spacer (52) or the dynamic pressure pipe (54) is fastened to an intermediate flange (50) which can be inserted between one of the housing flanges (42 and 44 respectively) and the wall.